C. F. Keil and Franz Delitzsch on Genesis 6:17-21

Gen 6:17-21

Noah was to build this ark, because God was about to bring a flood upon the earth, and would save him, with his family, and one pair of every kind of animal. מבּוּל, (the flood), is an archaic word, coined expressly for the waters of Noah (Isa 54:9), and is used nowhere else except Psa 29:10. הארץ על מים is in apposition to mabbul: “I bring the flood, waters upon the earth, to destroy all flesh, wherein is a living breath” (i.e., man and beast). With Noah, God made a covenant. On בּרית see Gen 15:18. As not only the human race, but the animal world also was to be preserved through Noah, he was to take with him into the ark his wife, his sons and their wives, and of every living thing, of all flesh, two of every sort, a male and a female, to keep them alive; also all kinds of food for himself and family, and for the sustenance of the beasts.