Genesis 7:2

“Of every clean beast thou shalt take to thee by sevens, etc.] From hence it appears, that the distinction of clean and unclean beasts, at least for sacrifice, if not for food, was known before the flood, and so before the law of Moses; though some think this is said by anticipation, and as providing a large stock of such creatures for the propagation of their species; because they would be most serviceable to men both for food and sacrifice: but as it is certain that sacrifices were offered ever since the fall of man; by the same way, namely, by divine revelation, that men were taught to sacrifice creatures as typical of the sacrifice of Christ, they were directed what sort of creatures to…”

“Of every clean beast . . . fowls--Pairs of every species of animals, except the tenants of the deep, were to be taken for the preservation of their respective kinds. This was the general rule of admission, only with regard to those animals which are styled "clean," three pairs were to be taken, whether of beasts or birds; and the reason was that their rapid multiplication was a matter of the highest importance, when the earth should be renovated, for their utility either as articles of food or as employed in the service of man. But what was the use of the seventh? It was manifestly reserved for sacrifice; and so that both during Noah's residence in the ark, and after his return to dry land,…”

“- The Ark Was Entered 2. טהור ṭâhôr “clean, fit for food or sacrifice.” 4. יקוּם yeqûm “standing thing; what grows up, whether animal or plant.” Compare קמה qāmâh “stalk, or standing corn.” Genesis 7:1-4 Here is found the command to enter the ark. The general direction in the preceding chapter was given many years ago, before the ark was commenced. Now, when it is completed, a more specific command is issued. “For thee have I seen righteous before me.” Noah has accepted the mercy of God, is therefore set right in point of law, and walks aright in point of practice. The Lord recognizes this indication of an adopted and renewed son. “In this age” he and his were the solitary family so…”

“Here are necessary orders given concerning the brute creatures that they were to be preserved alive with Noah in the ark. He must carefully preserve every species, that no tribe, no, not the least considerable, might entirely perish out of the creation. Observe in this: God's care for man. Doth God take care for oxen? Co1 9:9, or was it not rather for man's sake that this care was taken? Even the unclean beasts were preserved alive in the ark, that were least valuable. For God's tender mercies are over all his works, and not only over those that are of most use. Yet more of the clean were preserved than of the unclean. Because the clean were most for the service of man; and therefore in…”

“7:2 of each animal I have approved: In addition to the animals that were to repopulate the earth, these “clean” animals were for food and for Noah’s sacrifice after the flood (8:20-21). This passage does not use the precise technical language that is found in the regulations concerning “clean” and “unclean” given to Israel at Sinai (see Lev 11; Deut 14:3-12), but the underlying concept is the same (perhaps God revealed it directly to Noah).”

“every clean: Gen 7:8, Gen 6:19-21, Gen 8:20; Lev. 11:1-47; Deut. 14:1-21; Act 10:11-15 sevens: Heb. seven, seven not: Lev 10:10; Eze 44:23 Genesis 7:4”