For, behold, I give you space of seven days; if they will be converted, it shall be forgiven them; but if they will not be converted, after a time of days yet seven, I will cause rain to come down upon the earth forty days and forty nights, and will destroy all bodies of man and of beast upon the earth.
Seven Days for the Generation of the Flood to Repent
Targum Pseudo-Jonathan on Genesis 7:4