Sforno on Genesis 6:9/ספורנו על בראשית ו׳:ט׳

1תולדות נח, a reference to his history, commencing with his own life and continuing with that of his offspring.

2צדיק, in his deeds,

3תמים, in his attitudes,

4בדורותיו, according to the generations during which he lived. They included part of the generation of Metushelach, of Lemech, and those during the 600 years preceding the deluge.

5את האלוקים התהלך נח, he walked in G’d’s way trying to be helpful to others, and to instruct and if necessary to rebuke them, as our sages pointed out. This is also in accordance with what the historian Berussi Hacaldaii (3rd century B.C.) wrote about him.