Genesis 7:4

For yet seven days
Or one week more, after the above orders were given, which, the Jews say, were for the mourning at Methuselah's death; others, that they were an additional space to the one hundred and twenty given to the old world for repentance; in which time some might truly repent, finding that the destruction of the world was very near, and who might be saved from everlasting damnation, though not from perishing in the flood: but it rather was a space of time proper for Noah to have, to settle himself and family, and all the creatures in the ark, and dispose of everything there, in the best manner, for their sustenance and safety: and I will cause it to rain upon the earth forty days and forty
nights:
this was not an ordinary but an extraordinary rain, in which the power and providence of God were eminently concerned, both with respect to the continuance of it, and the quantity of water that fell: and every living substance that I have made will I destroy from off
the face of the earth:
not every substance that has a vegetative life, as plants, herbs, and trees, which were not destroyed, see ( Genesis 8:11 ) but every substance that has animal life, as fowls, cattle, creeping things, and men.