Short answer
The Buddhist scriptures give opposite answers in his name. In the Pali texts, a general named Siha has meat fetched for a meal for the Buddha and his monks. The Buddha then rules that a monk may not knowingly eat meat from an animal killed for him. Elsewhere he says meat may be eaten if the monk has not seen, heard or suspected that it was killed for him. In the Lankavatara Sutra, a Mahayana scripture, the Buddha forbids meat to everyone. He says he has never permitted it to anyone, and that the claim he allowed it to his monks or himself has no foundation. Its own translator calls that chapter a later addition. So one of the two puts words in the Buddha's mouth. The Qur'an gives its food laws in God's (﷾) own words.
Full explanation
The Pali texts: meat, with a condition
Jivaka, a physician, asked the Buddha whether he eats meat from animals killed for him. The Buddha says meat may not be eaten in three cases: if it is seen, heard or suspected that the animal was killed for the monk. Otherwise it may be eaten. In the monks' rule book, the Vinaya, a general named Siha sends for meat to serve the Buddha and the monks. Afterwards the Buddha rules that no one may knowingly eat meat from an animal killed for that purpose.
“In three cases I say that meat may not be eaten: it’s seen, heard, or suspected. These are three cases in which meat may not be eaten. In three cases I say that meat may be eaten: it’s not seen, heard, or suspected. These are three cases in which meat may be eaten.”
“Go, my friend, and see if there is any meat to be had.”
“Let no one, O Bhikkhus, knowingly eat meat (of an animal) killed for that purpose. Whosoever does so, is guilty of a dukkata offence.”
The Lankavatara Sutra: no meat at all
The Lankavatara Sutra, a Mahayana scripture, gives a whole chapter to meat. There the Buddha forbids meat to everyone, in any form and any place. He says he has never permitted it to anyone, does not and will not, and that the claim he allowed it to his monks or himself has no foundation whatever.
The Buddha forbids meat to all, in any form, manner and place, once and for all. He says that he has not permitted meat-eating to anyone, does not permit it and will not permit it, and that the claim that he permitted his monk disciples, or himself, to eat meat has no foundation whatever.
Two rulings in one name
Both scriptures speak in the Buddha's own voice, and they cannot both be his. The Pali Buddha allows meat that was not killed for the monk. The Lankavatara Buddha says he never allowed it at all. Suzuki, who translated the Lankavatara, notes that its meat chapter is a later addition, and that the early Buddhists probably did eat meat. So one of these scriptures puts a ruling in the Buddha's mouth that he did not give.
“In three cases I say that meat may not be eaten: it’s seen, heard, or suspected. These are three cases in which meat may not be eaten. In three cases I say that meat may be eaten: it’s not seen, heard, or suspected. These are three cases in which meat may be eaten.”
The Buddha forbids meat to all, in any form, manner and place, once and for all. He says that he has not permitted meat-eating to anyone, does not permit it and will not permit it, and that the claim that he permitted his monk disciples, or himself, to eat meat has no foundation whatever.
Suzuki, the sutra's translator, notes that the chapter on meat-eating is a later addition to the text, and that meat-eating was probably practised more or less among the earlier Buddhists.
Food laws in God's (﷾) own words
The Qur'an gives its food laws as God's (﷾) own word. It says all good and pure things are lawful, and it names what is forbidden: carrion, blood, pork, and what is offered to anyone besides Allah (﷾). It tells believers to eat of what has been slaughtered in Allah's (﷾) name.
“This day are (all) things good and pure made lawful unto you. The food of the People of the Book is lawful unto you and yours is lawful unto them. (Lawful unto you in marriage) are (not only) chaste women who are believers, but chaste women among the People of the Book, revealed before your time,- when ye give them their due dowers, and desire chastity, not lewdness, nor secret intrigues if any one rejects faith, fruitless is his work, and in the Hereafter he will be in the ranks of those who have lost (all spiritual good).”
“He hath only forbidden you dead meat, and blood, and the flesh of swine, and that on which any other name hath been invoked besides that of Allah. But if one is forced by necessity, without wilful disobedience, nor transgressing due limits,- then is he guiltless. For Allah is Oft-forgiving Most Merciful.”
“Say: "I find not in the message received by me by inspiration any (meat) forbidden to be eaten by one who wishes to eat it, unless it be dead meat, or blood poured forth, or the flesh of swine,- for it is an abomination - or, what is impious, (meat) on which a name has been invoked, other than Allah's". But (even so), if a person is forced by necessity, without wilful disobedience, nor transgressing due limits,- thy Lord is Oft-forgiving, Most Merciful.”
“So eat of (meats) on which Allah's name hath been pronounced, if ye have faith in His signs.”
Perspectives
Buddhist replies
The Pali texts record the Buddha's own rule, and the Lankavatara is a later text. Or both are right: the first rule was for monks who had to take what they were given. The second is a higher ideal for bodhisattvas.
The Lankavatara is a later Mahayana text, so the Pali rule is the Buddha's real teaching.
Rebuttal
Then Buddhists who honour the Lankavatara as the Buddha's word follow a ruling he never gave. And the Lankavatara says the very opposite: that the claim he allowed meat has no foundation. One of the two puts words in his mouth.
Both are true at different levels. Monks begging for alms had to take what they were given, while bodhisattvas hold a higher ideal of compassion.
Rebuttal
The Lankavatara does not speak of levels. It says the Buddha has never permitted meat to anyone, does not and will not, and that the claim he permitted it to his monks or himself is baseless. The Pali Vinaya has him make a rule permitting it after a meal with meat.
The Islamic perspective
The Pali texts and the Lankavatara give the Buddha opposite rulings on meat, and the Lankavatara's own translator calls its chapter a later addition. The Qur'an gives its food laws in God's (﷾) own words.
In the Pali texts the Buddha allows meat, with one exception. It must not be seen, heard or suspected to have been killed for the monk.
In the Lankavatara Sutra the Buddha says he never permitted meat to anyone. Its translator calls that chapter a later addition.
The Qur'an makes good and pure things lawful and names what is forbidden.