Genèse 6:8

But Noah, who was righteous, found favour before the Lord.

BUT NOAH FOUND GRACE IN THE EYES OF THE ETERNAL. The meaning thereof is that all his deeds were pleasing and sweet before Him. Similarly: For thou hast found grace in My sight, and I know thee by name. This is like the verses: And He gave him favor in the sight of the keeper of the prison; And Esther obtained favor in the sight of all of them that looked upon her. Scripture mentions this in contrast to what it said concerning his [Noah’s] generation, namely, that all their deeds brought grief before Him, blessed be He. But of Noah it says that he found grace in His eyes, and afterwards it tells. why he was pleasing before G-d: because he was a perfectly righteous man.
Noach

ונח מצא חן, this is an explanation why also his sons and daughters (in law) were saved. Noach’s personal merits did not entitle him to demand from G’d that He also save them on the strength of his merits. They required special חנינה, clemency (based on Bereshit Rabbah 29,1. According to the verse in Ezekiel 14,14-19 G’d discusses with the prophet the three men Noach, Daniel, and Job as possessing sufficient merit to be saved themselves, but as not having sufficient merit to entitle their families to be saved [the rider there is if these three men had lived in the (wicked) city described by G’d to Ezekiel, the men of the city would not have been saved by their presence.] The reason why these individuals were not as effective in saving the people around them was that they were devout and pious for themselves without trying to use their influence to convert their contemporaries to adopt their lifestyles. This is what made them basically different from Avraham, Moses and Samuel and others like them, who went out to win converts. This is what the sages in Pessachim 87 had in mind when they described such people. The Talmud distinguishes between people who זכו ללמוד ולא זכו ללמד, “acquired the merit of studying Torah, but did not acquire the merit of disseminating Torah knowledge.” [Rashi in the Talmud contrasts Daniel’s activities in Eylam (the country of which Shushan was the capital) with those of Ezra in Babylon. The former, while learning Torah, did not teach it, the latter both learned and taught with very beneficial results. Ed.] A righteous person who keeps perfecting himself is entitled to being saved personally, but he is not entitled thereby to save others on his account. While Noach did rebuke the men of his time, he did not travel the extra mile to try and convert them to do good. Our sages in Berachot 19 comment that “if you see a Torah scholar who was guilty of something improper during the day, do not accuse him of anything in your mind during the following night for surely he has done teshuvah in the interval.”

'ונח מצא חן בעיני ה, he found favour due to good deeds performed by him. The Torah uses the same expression in Exodus 33,17 when G’d tells Moses that he had found favour in His eyes. His deeds had been pleasing to G’d. In Bereshit Rabbah 28,9, Rabbi Acha son of Kahana expresses surprise at the words ונח מצא חן בעיני ה', saying that the wording implies that Noach, in his own right, could not have claimed the right of survival, except for the circumstance that he “found favour in the eyes of the Lord, i.e. G’d had to search for a reason to let him survive. [He bases himself on the whole verse being superfluous, as Noach’s merits are discussed in the following verses. Rabbi Einhorn’s comment on that Midrash. Ed.]