Page 131 - BERESHIT

These seven days were the period of mourning for Mesushelach who had
died. A third Midrash states that Noach entered the Ark in the middle of
the day, to counter their argument that had Noach entered by day they
would have prevented his evacuation.
What reason was there to be sad about the destruction of that wicked
generation? Their actions affected the whole of Creation and caused the
earth to be corrupt. Why was Hashem so distressed? Hashem wanted them
to do teshuvah and to rectify their sins. They had the ability to change
their lives and save humanity, and instead wasted it away.
The “seven mitzvot of Bnei Noach” correspond to the seven days of
Creation. By keeping their mitzvot, the earth could have had a basis and
merit to exist. Unfortunately, this was not sufficient, as we find Noach’s
descendants breaking their laws and disregarding the basic tenets of belief.
Thus it was necessary for Hashem to give 613 mitzvot to help preserve
mankind from self-destruction. These mitzvot have a direct correlation to
the organs and tendons in the human body. By keeping the mitzvot, we
become worthy of existing and entitled to live off the merit of their
righteous deed.

“And Noach, his children, his wife and the
wives of his children, all entered with him into
the Ark ahead of the waters of the Flood”

(Bereishit 7:7)