Genesis 9:3-4

3. Every moving thing that liveth shall be meat for you. The Lord proceeds further, and grants animals for food to men, that they may eat their flesh. And because Moses now first relates that this right was given to men, nearly all commentators infer, that it was not lawful for man to eat flesh before the deluge, but that the natural fruits of the earth were his only food. But the argument is not sufficiently firm. For I hold to this principle; that God here does not bestow on men more than he had previously given, but only restores what had been taken away, that they might again enter on the possession of those good things from which they had been excluded. For since they had before offered sacrifices to God, and were also permitted to kill wild beasts, from the hides and skins of which, they might make for themselves garments and tents, I do not see what obligation should prevent them from the eating of flesh. But since it is of little consequence what opinion is held, I affirm nothing on the subject. This ought justly to be deemed by us of greater importance, that to eat the flesh of animals is granted to us by the kindness of God; that we do not seize upon what our appetite desires, as robbers do, nor yet tyrannically shed the innocent blood of cattle; but that we only take what is offered to us by the hand of the Lord. We have heard what Paul says, that we are at liberty to eat what we please, only we do it with the assurance of conscience, but that he who imagines anything to be unclean, to him it is unclean, (Romans 14:14.) And whence has this happened to man, that he should eat whatever food he pleased before God, with a tranquil mind, and not with unbridled license, except from his knowing, that it has been divinely delivered into his hand by the right of donation? Wherefore, (the same Paul being witness,) the word of God sanctifies the creatures, that we may purely and lawfully feed on them, (1 Timothy 4:5.) Let the adage be utterly rejected which says, ‘that no one can feed and refresh his body with a morsel of bread, without, at the same time, defiling his soul.’ Therefore it is not to be doubted, that the Lord designed to confirm our faith, when he expressly declares by Moses, that he gave to man the free use of flesh, so that we might not eat it with a doubtful and trembling conscience. At the same time, however, he invites us to thanksgiving. On this account also, Paul adds “prayer” to the “word,” in defining the method of sanctification in the passage recently cited.

And now we must firmly retain the liberty given us by the Lord, which he designed to be recorded as on public tables. For, by this word, he addresses all the posterity of Noah, and renders this gift common to all ages. And why is this done, but that the faithful may boldly assert their right to that which, they know, has proceeded from God as its Author? For it is an insupportable tyranny, when God, the Creator of all things, has laid open to us the earth and the air, in order that we may thence take food as from his storehouse, for these to be shut up from us by mortal man, who is not able to create even a snail or a fly. I do not speak of external prohibition; but I assert, that atrocious injury is done to God, when we give such license to men as to allow them to pronounce that unlawful which God designs to be lawful, and to bind consciences which the word of God sets free, with their fictitious laws. The fact that God prohibited his ancient people from the use of unclean animals, seeing that exception was but temporary, is here passed over by Moses.