(2) בדורותיו IN HIS GENERATIONS — Some of our Rabbis explain it (this word) to his credit: he was righteous even in his generation; it follows that had he lived in a generation of righteous people he would have been even more righteous owing to the force of good example. Others, however, explain it to his discredit: in comparison with his own generation he was accounted righteous, but had he lived in the generation of Abraham he would have been accounted as of no importance (cf. Sanhedrin 108a).
(3) ויתעצב אל לבו AND IT GRIEVED HIM AT HIS HEART— He mourned at the failure of His handiwork. Similarly (2 Samuel 19:3) ‘The king grieved (נעצב) for his son”. (Similarly here: God grieved for his (man’s) heart: that it had changed from good to bad). The following extract from the Midrash Rabbah I am writing in order that you may know how to refute the arguments of certain heretics: A gentile once asked Rabbi Joshua, the son of Korcha, saying to him, “Do you not admit that the Holy One, blessed be He, knows what is to happen in the future?” He replied, “Yes.” The gentile retorted, “But is it not written ‘and He was grieved in His heart’?” He answered: “Have you ever had a son born to you?” The reply was “Yes.” He asked (the gentile): “And what did you do?” He replied: “I rejoiced and I made others rejoice also.” The Rabbi asked him: “But did you not know that he must die?” The heathen replied: “At the time of joy, let there be joy, at the time of mourning let there be mourning”. The Rabbi then said: “Such, too, is the way of the Holy One, blessed be He: although it was clear to Him that in the end men would sin and would be destroyed, He did not refrain from creating them for the sake of the righteous men who were to issue from them” (Genesis Rabbah 27:4).
(1) ונactually, It wasn't because he was actually fit to be saved, rather it was because he found favor in the eyes of Hashem.
(3) את האלהים התהלך נח NOAH WALKED WITH GOD — In the case of Abraham Scripture says, (Genesis 24:40) ‘‘[God] before whom I walked”; Noah needed God’s support to uphold him in righteousness, Abraham drew his moral strength from himself and walked in his righteousness by his own effort (Genesis Rabbah 30:10).
(2) מבול A FLOOD — so called because it ruined (בלה) everything; because it cast everything into confusion (בלל), and because it brought (הוביל from root יבל) everything down from the heights to a lower level.
(ג) וְזֹאת הַבְּרָכָה, זֶה שֶׁאָמַר הַכָּתוּב (משלי לא, כט): רַבּוֹת בָּנוֹת עָשׂוּ חָיִל וְאַתְּ עָלִית עַל כֻּלָּנָה, מַהוּ וְאַתְּ עָלִית עַל כֻּלָּנָה, מְדַבֵּר בְּמשֶׁה, עַל שֶׁנִּתְעַלָּה יוֹתֵר מִן הַכֹּל. כֵּיצַד, אָדָם הָרִאשׁוֹן אוֹמֵר לְמשֶׁה אֲנִי גָּדוֹל מִמְּךָ שֶׁנִּבְרֵאתִי בְּצַלְּמוֹ שֶׁל הַקָּדוֹשׁ בָּרוּךְ הוּא, מִנַּיִן, שֶׁנֶּאֱמַר (בראשית א, כז): וַיִּבְרָא אֱלֹהִים אֶת הָאָדָם בְּצַלְמוֹ, אוֹמֵר לוֹ משֶׁה, אֲנִי נִתְעַלֵּיתִי יוֹתֵר מִמְּךָ, אַתָּה כָּבוֹד שֶׁנִּתַּן לְךָ נִטַּל מִמְּךָ, שֶׁנֶּאֱמַר (תהלים מט, יג): וְאָדָם בִּיקָר בַּל יָלִין, אֲבָל אֲנִי זִיו הַפָּנִים שֶׁנָּתַן לִי הַקָּדוֹשׁ בָּרוּךְ הוּא, עִמִּי הוּא, מִנַּיִן, שֶׁנֶּאֱמַר (דברים לד, ז): לֹא כָהֲתָה עֵינוֹ וְלֹא נָס לֵחֹה. דָּבָר אַחֵר, נֹחַ אָמַר לְמשֶׁה אֲנִי גָּדוֹל מִמְּךָ שֶׁנִּצַּלְתִּי מִדּוֹר הַמַּבּוּל, אָמַר לוֹ משֶׁה אֲנִי נִתְעַלֵּיתִי יוֹתֵר מִמְּךָ, אַתָּה הִצַּלְתָּ אֶת עַצְמְךָ וְלֹא הָיָה בְךָ כֹּחַ לְהַצִּיל אֶת דּוֹרְךָ, אֲבָל אֲנִי הִצַּלְתִּי אֶת עַצְמִי וְהִצַּלְתִּי אֶת דּוֹרִי כְּשֶׁנִּתְחַיְּבוּ כְּלָיָה בָּעֵגֶל, מִנַּיִן, שֶׁנֶּאֱמַר (שמות לב, יד): וַיִּנָּחֶם ה' עַל הָרָעָה אֲשֶׁר דִּבֶּר לַעֲשׂוֹת לְעַמּוֹ, לְמָה הַדָּבָר דּוֹמֶה לִשְׁתֵּי סְפִינוֹת שֶׁהָיוּ בַּיָּם וְהָיוּ בְּתוֹכָן שְׁנֵי קַבַּרְנִיטִים, אֶחָד הִצִּיל אֶת עַצְמוֹ וְלֹא הִצִּיל אֶת סְפִינָתוֹ
(2) מפני 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).