Short answer
Islam has a law of war, set down in the Qur'an and by the Prophet Muhammad (ﷺ). Many early scholars count one verse as the first to allow fighting. It was given to people driven from their homes. It names churches and synagogues among the houses of God (﷾) that fighting protects. The Qur'an allows fighting only against those who fight, and never beyond the limits. They must accept peace when the enemy offers it, and give safety to an enemy who asks. Women and children must not be killed. The dead must not be mutilated, pledges must not be broken, and no one may be punished by fire. When his general broke these limits, the Prophet (ﷺ) publicly disowned what he had done. The jurist al-Shaybani wrote a whole book on this law more than eight hundred years before Hugo Grotius, often called the father of international law. None of this gives any individual or group a right to fight: in Islamic law war is for the ruler of a state alone, and Muslims keep the law of whatever country they live in (17:34).
Full explanation
The first permission to fight
In Mecca the Muslims were persecuted and driven from their homes, and they did not fight back. Many early scholars, as Ibn Kathir (a Qur'an commentator of the fourteenth century) reports, held this to be the first verse that allowed fighting. It gives the permission to those who were wronged. It then gives a reason: if God (﷾) did not check one people by means of another, monasteries, churches, synagogues and mosques would be pulled down. The first permission to fight in Islam names the houses of worship of Christians and Jews, before the mosques, among those the fighting protects. The Prophet (ﷺ) acted under this permission.
“To those against whom war is made, permission is given (to fight), because they are wronged;- and verily, Allah is most powerful for their aid;- (They are) those who have been expelled from their homes in defiance of right,- (for no cause) except that they say, "our Lord is Allah". Did not Allah check one set of people by means of another, there would surely have been pulled down monasteries, churches, synagogues, and mosques, in which the name of Allah is commemorated in abundant measure. Allah will certainly aid those who aid his (cause);- for verily Allah is full of Strength, Exalted in Might, (able to enforce His Will).”
Explains that the verse came when the Prophet (ﷺ) and his Companions had been driven out of Mecca, and reports that several of the early scholars said it was the first verse revealed about fighting.
The limits the Qur'an sets
The Qur'an allows fighting only against those who fight, and forbids crossing the limits. When the enemy inclines to peace, Muslims must incline to it. Those who withdraw and offer peace may not be attacked. An enemy fighter who asks for protection must be given it and escorted to safety. For captives, the Qur'an names two ways to end their captivity: freeing them as a favour, or for ransom. Justice is owed even to people one hates, and kindness to those who do not fight. The Prophet (ﷺ) lived by these verses.
“Fight in the cause of Allah those who fight you, but do not transgress limits; for Allah loveth not transgressors.”
“But if the enemy incline towards peace, do thou (also) incline towards peace, and trust in Allah: for He is One that heareth and knoweth (all things).”
“Except those who join a group between whom and you there is a treaty (of peace), or those who approach you with hearts restraining them from fighting you as well as fighting their own people. If Allah had pleased, He could have given them power over you, and they would have fought you: Therefore if they withdraw from you but fight you not, and (instead) send you (Guarantees of) peace, then Allah Hath opened no way for you (to war against them).”
“If one amongst the Pagans ask thee for asylum, grant it to him, so that he may hear the word of Allah; and then escort him to where he can be secure. That is because they are men without knowledge.”
“Therefore, when ye meet the Unbelievers (in fight), smite at their necks; At length, when ye have thoroughly subdued them, bind a bond firmly (on them): thereafter (is the time for) either generosity or ransom: Until the war lays down its burdens. Thus (are ye commanded): but if it had been Allah's Will, He could certainly have exacted retribution from them (Himself); but (He lets you fight) in order to test you, some with others. But those who are slain in the Way of Allah,- He will never let their deeds be lost.”
“O ye who believe! stand out firmly for Allah, as witnesses to fair dealing, and let not the hatred of others to you make you swerve to wrong and depart from justice. Be just: that is next to piety: and fear Allah. For Allah is well-acquainted with all that ye do.”
“Allah forbids you not, with regard to those who fight you not for (your) Faith nor drive you out of your homes, from dealing kindly and justly with them: for Allah loveth those who are just.”
The Prophet's (ﷺ) orders to his commanders
When a woman was found killed in one of his campaigns, the Prophet (ﷺ) forbade the killing of women and children. He told every commander he sent out not to steal from the spoils, break a pledge, mutilate the dead or kill children. In his campaigns, before any battle, the commander was to offer the enemy army a way out of the fighting: accepting Islam, or paying the jizya (the tax paid by non-Muslims under Muslim protection). If they agreed, the army had to hold back. These were orders for an army facing an army in his time. On one expedition he first ordered that two named men be burned if they were caught. Before the troops left he withdrew that order, because only Allah (﷾) punishes with fire, and told them to put the men to death instead. He warned that whoever kills a person under treaty with the Muslims will not smell the fragrance of Paradise.
Ibn Umar reports that a woman was found killed during one of the Prophet's (ﷺ) campaigns, and the Prophet forbade the killing of women and children.
Ibn Umar reports that a woman was found killed in one of the Prophet's (ﷺ) battles, and the Prophet forbade the killing of women and children.
Buraida reports that when the Prophet (ﷺ) appointed a commander he told him to fear Allah and to be good to his men, and not to steal from the spoils, break a pledge, mutilate the dead or kill children. Before any fighting the enemy was to be offered three choices: accept Islam; if not, pay the jizya, and then the Muslims must hold back from them; and only if both were refused, fight.
Abu Huraira reports that the Prophet (ﷺ) told a raiding party to burn two named men, then took the order back before they left: only Allah punishes with fire, so if they found them they were to kill them, not burn them.
Abdullah ibn Amr reports that the Prophet (ﷺ) said that whoever kills a person who has a treaty with the Muslims will not smell the fragrance of Paradise, though its fragrance reaches a distance of forty years.
The limits on a Muslim army
- Fight only those who fight you, and never beyond the limits.
- Accept peace when the enemy offers it.
- Give safety to an enemy who asks for it.
- Do not kill women or children.
- Do not mutilate the dead or break a pledge.
- Punish no one by fire.
- Only the ruler of a state may declare war.
He disowned his own general's breach
Khalid ibn al-Walid was one of the Prophet's (ﷺ) leading generals. Sent to the tribe of Jadhima, he killed men who had been trying to tell him they had become Muslims. When the Prophet (ﷺ) heard of it, he raised his hands and said twice that he was free of what Khalid had done. The limits bound his own army, and he disowned his own general's breach of them in public. Classical law was written for the Muslim states of its time. It also knew wars that were not purely defensive, such as the campaign that followed Qur'an 9:29, which has its own page. Every one of them was for the ruler of a state to declare, and the same limits governed them all.
Khalid ibn al-Walid, sent to the tribe of Jadhima, killed and captured men who had been trying to say they had become Muslims. When the Prophet (ﷺ) heard, he raised his hands and said twice: O Allah, I am free of what Khalid has done.
Ibn Qudamah, a Hanbali jurist, holds that the matter of jihad is entrusted to the ruler (imam) and his judgement, and that the people must obey him in it. He makes one exception: if an enemy attacks suddenly and there is no time to ask the ruler, the people may defend themselves without his permission. He also holds that a Muslim who enters a non-Muslim land under a promise of safety (aman) may not betray its people or take their property, because the safety was given on the understanding that he would not betray them, even if this was not said in words.
The Bible's law of war
The New Testament gives no law of war. John the Baptist told soldiers to "Do violence to no man" and be content with their wages. That is advice about each soldier's own conduct. It says nothing about when a war may be fought or who may be spared. "Love your enemies" is a command to the soul, not a rule for an army. So the Christian Bible's only law of war is in its Old Testament. The Old Testament has some rules. An army must first offer a city peace, and it must not cut down fruit trees in a siege. But for the cities of Canaan it commands that nothing that breathes be left alive. Against Amalek, Saul is told to kill man and woman, infant and suckling. The Book of Numbers says that after the war on Midian, Moses ordered every boy and every woman who had known a man to be killed. For Canaan, Amalek and Midian, the command on women and children is the opposite of the one the Prophet (ﷺ) gave. Beyond the law, Ezekiel (sixth century BC) tells of a vision. In it he hears an order to slay old and young, maids, little children and women.
“And the soldiers likewise demanded of him, saying, And what shall we do? And he said unto them, Do violence to no man, neither accuse any falsely; and be content with your wages.”
“But I say unto you, Love your enemies, bless them that curse you, do good to them that hate you, and pray for them which despitefully use you, and persecute you;”
“When thou comest nigh unto a city to fight against it, then proclaim peace unto it.”
“When thou shalt besiege a city a long time, in making war against it to take it, thou shalt not destroy the trees thereof by forcing an axe against them: for thou mayest eat of them, and thou shalt not cut them down (for the tree of the field is man’s life) to employ them in the siege: Only the trees which thou knowest that they be not trees for meat, thou shalt destroy and cut them down; and thou shalt build bulwarks against the city that maketh war with thee, until it be subdued.”
“But of the cities of these people, which the Lord thy God doth give thee for an inheritance, thou shalt save alive nothing that breatheth:”
“Now go and smite Amalek, and utterly destroy all that they have, and spare them not; but slay both man and woman, infant and suckling, ox and sheep, camel and ass.”
“And Moses said unto them, Have ye saved all the women alive? Behold, these caused the children of Israel, through the counsel of Balaam, to commit trespass against the Lord in the matter of Peor, and there was a plague among the congregation of the Lord. Now therefore kill every male among the little ones, and kill every woman that hath known man by lying with him. But all the women children, that have not known a man by lying with him, keep alive for yourselves.”
“And to the others he said in mine hearing, Go ye after him through the city, and smite: let not your eye spare, neither have ye pity: Slay utterly old and young, both maids, and little children, and women: but come not near any man upon whom is the mark; and begin at my sanctuary. Then they began at the ancient men which were before the house.”
Where each law of war was set down
Christian thinkers who set out a law of war could not find one in the New Testament Gospels. Ambrose and Augustine, bishops of the fourth and fifth centuries, drew on the Bible. Ambrose of Milan also drew on Cicero, a Roman orator. Cicero taught that war is only a last resort, waged so that people may live in peace. The Qur'an too commands accepting peace when the enemy offers it. Centuries later, Thomas Aquinas, a Christian scholar of the thirteenth century, set out three conditions for a just war, building on Augustine. The Muslim jurist Muhammad ibn al-Hasan al-Shaybani, who died in 805, wrote on the law of war and peace as a field of its own. He covered declaring war, who may not be harmed, prisoners, envoys and treaties. He wrote two books on it, a shorter Siyar and the longer al-Siyar al-Kabir. The shorter one is in English in Majid Khadduri's translation. That was more than eight hundred years before Hugo Grotius, a Dutch jurist, wrote On the Law of War and Peace in 1625. It was more than a thousand years before the first Geneva Convention of 1864. The Muslims had their law of war from revelation, in the Qur'an and the teaching of the Prophet (ﷺ).
Cicero teaches that there are two ways of settling a dispute, by discussion and by force, and that force is only to be used when discussion fails. The only excuse for war is that we may live in peace unharmed, and a war is just only if it is formally declared after a demand for redress. Ambrose, bishop of Milan, later wrote his own On Duties as a Christian reworking of this book.
Asks whether it is always sinful to wage war, and answers that three things are needed for a war to be just: the authority of the ruler, a just cause, and a right intention. The article builds on quotations from Augustine.
An English translation, with a long introduction, of the siyar (the law of war and peace) of the jurist Muhammad ibn al-Hasan al-Shaybani, who died in 805. It sets out Islamic law on declaring war, who may not be harmed, the treatment of prisoners and envoys, safe-conduct, and the keeping of treaties.
On the Law of War and Peace, the Dutch jurist's treatise on when war is lawful and how it must be conducted. Europe counts it as a founding work of international law.
- Before 805
al-Shaybani
The Muslim jurist writes on the law of war and peace as a field of its own.
- 1200s
Thomas Aquinas
Sets out three conditions for a just war, building on Augustine.
- 1625
Hugo Grotius
On the Law of War and Peace, which Europe counts a founding work of international law.
- 1864
The first Geneva Convention
More than a thousand years after al-Shaybani.
Verse by verse
Deuteronomy 20:16 — Torah, Devarim, chapter 20, verse 16
“But of the cities of these people, which the Lord thy God doth give thee for an inheritance, thou shalt save alive nothing that breatheth:”
Cited for
Christians read the commands against Canaan and Amalek as God's judgement on those nations alone. They say it was for a single time in history and is not a rule for today.
The response
Even read that way, these are commands in the Christian Bible's only law of war. For Canaan and Amalek they order the killing of women and infants. The Prophet (ﷺ) was sent with the reverse. When one woman was found killed, he forbade the killing of women and children, and he told every commander not to kill children.
Where it lands — On women and children in war, the Prophet's (ﷺ) law protects the very people the Bible's commands against Canaan and Amalek did not spare.
Sahih al-Bukhari 3012 — Kitab al-Jihad wa al-Siyar (Book of Fighting for the Cause of Allah), hadith 3012
al-Sa'b ibn Jaththama reports that the Prophet (ﷺ) was asked about attacking pagan fighters at night when their women and children might be exposed to harm, and replied that they are from them.
Cited for
Critics say the Prophet (ﷺ) allowed women and children to be killed in night raids.
The response
The report is about deaths no one intended. In the dark, women and children could not be told apart from the fighters. Al-Nawawi (a scholar of the thirteenth century) and most scholars explain this. It never allows anyone to aim at them, and the Prophet's (ﷺ) ban on killing them on purpose stands.
Where it lands — The night-raid report speaks of unintended deaths; the ban on killing women and children stands.
Perspectives
Christian just war teaching
Christians hold that Jesus taught love of enemies. War may be just, they say, only under strict conditions, set out by Augustine and Aquinas.
Jesus commanded his followers to love their enemies and do good to those who hate them.
Rebuttal
Islam also commands justice even to enemies, and kindness to those who do not fight. But Jesus' command is a rule for each believer's own dealings. It does not say when an army may fight or whom it must spare. The Christian Bible's only law of war is in its Old Testament. The Qur'an and the Prophet (ﷺ) set those limits.
Aquinas taught that a just war needs the ruler's authority, a just cause and a right intention.
Rebuttal
Aquinas did set out these three conditions for when a war is just. Islam too gives the permission to fight to those who were wronged, and holds that war belongs to a lawful ruler. Islam's law goes on to fix limits on how war is fought. Al-Shaybani, who died in 805, wrote that law down as a field of its own.
The Islamic perspective
Islam permits fighting only by a lawful state, under a law given by revelation. The Qur'an and the Prophet (ﷺ) set limits that protect women, children, the dead, envoys, people under treaty and any enemy who asks for safety. The Prophet (ﷺ) held his own army to them.
The first permission to fight was given to people who had been wronged and driven from their homes. It names churches and synagogues among the houses of God (﷾) that fighting protects.
The Qur'an forbids transgressing limits and commands accepting peace. It forbids attacking those who withdraw and offer peace, and orders protection for an enemy who asks for it.
The Qur'an names two ways to end a captive's captivity: freeing him as a favour, or for ransom.
The Prophet (ﷺ) forbade killing women and children, mutilating the dead, breaking pledges and punishing by fire.
Khalid, the Prophet's (ﷺ) own general, killed men who were trying to say they were Muslims. The Prophet (ﷺ) publicly disowned what he had done.
Justice is owed even to enemies, and kindness to those who do not fight.
The Bible commands that nothing that breathes be left alive in the cities of Canaan (Deuteronomy). It commands that the women and infants of Amalek be killed (1 Samuel). It says Moses commanded that the boys of Midian and every woman who had known a man be killed. The Prophet (ﷺ) forbade killing women and children.
Al-Shaybani, who died in 805, wrote on the Islamic law of war and peace. That was more than eight centuries before Grotius's book of 1625.