Genesis 7:2

Of every clean beast. Instruction to take more clean than unclean animals with him into the ark presupposes that Noah knew how to distinguish between the two classes. It is clear that this distinction did not originate with Moses. It reached back to the very earliest times, to divine instructions concerning sacrifices — for which only clean animals might be used (see Gen. 8:20).

Since ancient times the number of clean animals to be taken into the ark has been the subject of dispute among Bible translators and commentators. The Hebrew text, reading literally, “Thou shalt take to thee seven seven, a male with his female,” can be understood as meaning “seven pairs” or “seven of each kind” of animal. The LXX, Vulgate, and many ancient and modern scholars favor the translation “seven pairs,” whereas certain church Fathers, the Reformers, and in fact some scholars in all ages, have expressed themselves in favor of “seven individuals.” Whatever the exact explanation may be, it is obvious that more clean animals were to find room in the ark than unclean. Foreseeing the need for emergency food after the Flood had destroyed all vegetation, God knew man would need to eat, temporarily, the flesh of clean animals. Furthermore, they were needed for sacrificial purposes. For these obvious reasons God made provision to preserve enough clean animals that they might not become extinct. That in His first instructions to Noah (ch. 6:19) God made no distinction between clean and unclean animals can be explained by the fact that at that time, 120 years before the Flood, such minute instructions were not necessary (see on v. 9).