Genesis 9:4

But flesh with the life thereof, which is the blood - Though animal food was granted, yet the blood was most solemnly forbidden, because it was the life of the beast, and this life was to be offered to God as an atonement for sin. Hence the blood was ever held sacred, because it was the grand instrument of expiation, and because it was typical of that blood by which we enter into the holiest. 1. Before the deluge it was not eaten, because animal food was not in use. 2. After the deluge it was prohibited, as we find above; and, being one of the seven Noahic precepts, it was not eaten previously to the publication of the Mosaic law. 3. At the giving of the law, and at several times during the ministry of Moses, the prohibition was most solemnly, and with awful penalties renewed. Hence we may rest assured that no blood was eaten previously to the Christian era, nor indeed ever since by the Jewish people. 4. That the prohibition has been renewed under the Christian dispensation, can admit of little doubt by any man who dispassionately reads Acts 15:20, Acts 15:29; Acts 21:25, where even the Gentile converts are charged to abstain from it on the authority, not only of the apostles, but of the Holy Ghost, who gave them there and then especial direction concerning this point; see Acts 15:28; not for fear of stumbling the converted Jews, the gloss of theologians, but because it was one των επαναγκες τουτων, of those necessary points, from the burden (βαρος) of obedience to which they could not be excused. 5. This command is still scrupulously obeyed by the oriental Christians, and by the whole Greek Church; and why? because the reasons still subsist. No blood was eaten under the law, because it pointed out the blood that was to be shed for the sin of the world; and under the Gospel it should not be eaten, because it should ever be considered as representing the blood which has been shed for the remission of sins. If the eaters of blood in general knew that it affords a very crude, almost indigestible, and unwholesome ailment, they certainly would not on these physical reasons, leaving moral considerations out of the question, be so much attached to the consumption of that from which they could expect no wholesome nutriment, and which, to render it even pleasing to the palate, requires all the skill of the cook. See Leviticus 17:10.

The first restriction on the grant of animal food is thus expressed: "Flesh with its life, its blood, shall ye not eat." The animal must be slain before any part of it is used for food. And as it lives so long as the blood flows in its veins, the life-blood must be drawn before its flesh may be eaten. The design of this restriction is to prevent the horrid cruelty of mutilating or cooking an animal while yet alive and capable of suffering pain. The draining of the blood from the body is an obvious occasion of death, and therefore the prohibition to eat the flesh with the blood of life is a needful restraint from savage cruelty. It is also intended, perhaps, to teach that the life of the animal, which is in the blood, belongs not to man, but to God himself, who gave it. He makes account of it for atonement in sacrifice; otherwise it is to be poured on the ground and covered with dust Leviticus 17:11-13.

9:4 But flesh with the life thereof, which is the blood thereof, shall ye not eat - Blood made atonement for the soul, Lev 17:11. The life of the sacrifice was accepted for the life of the sinner. Blood must not be looked upon as a common thing, but must be poured out before the Lord, 2Sam 23:16. Mr. Henry indeed has a strange conceit, That this is only a prohibition to eat flesh. This does such apparent violence to the text, that to mention it, is sufficient.