Rashi on Genesis 7:7/רש"י על בראשית ז׳:ז׳

1נח ובניו NOAH AND HIS SONS — The men separately and the women separately, because they were forbidden to live together as man and wife since the world was living in a state of distress

2מפני מי המבול BECAUSE OF THE WATERS OF THE FLOOD — (מפני properly means ‘‘from before”) — Noah, also, was of those people who are wanting in faith: he believed and he did not believe that the Flood would come, and he would not enter the Ark until the waters forced him to do so (Genesis Rabbah 32:6).