Genesis 9:4

But flesh with the life thereof, which is the blood thereof, shall ye not eat.

But flesh ... the blood. The intention of this prohibition was to prevent those excesses of cannibal ferocity, in eating flesh of living animals, to which men in the earlier ages of the world were liable, which is still practised in Abyssinia, as well as in drinking blood, which was frequently done by the pagan. The reason assigned, "the blood is the life thereof," embodies a fact which ranks among the most remarkable discoveries of modern science, that the blood is the circulating principle of life, and therefore, being sacred to Him who is the giver of life, must be carefully poured out of every animal used for human food. This injunction was re-enacted by the Mosaic law, which forbade the eating of blood (Leviticus 3:17; Leviticus 7:20; Leviticus 19:25; Deuteronomy 12:16), and recommended the blood of the sacrifices to be sprinkled on the altar (Leviticus 17:11; Deuteronomy 12:23). The interdict applied to strangers as well as Israelites; and it was enforced also among the primitive Christians (Acts 15:20; Acts 15:29; Acts 21:25).