Musar for Pirkei Avot 5:2
עֲשָׂרָה דוֹרוֹת מֵאָדָם וְעַד נֹחַ, לְהוֹדִיעַ כַּמָּה אֶרֶךְ אַפַּיִם לְפָנָיו, שֶׁכָּל הַדּוֹרוֹת הָיוּ מַכְעִיסִין וּבָאִין עַד שֶׁהֵבִיא עֲלֵיהֶם אֶת מֵי הַמַּבּוּל. עֲשָׂרָה דוֹרוֹת מִנֹּחַ וְעַד אַבְרָהָם, לְהוֹדִיעַ כַּמָּה אֶרֶךְ אַפַּיִם לְפָנָיו, שֶׁכָּל הַדּוֹרוֹת הָיוּ מַכְעִיסִין וּבָאִין, עַד שֶׁבָּא אַבְרָהָם וְקִבֵּל עָלָיו שְׂכַר כֻּלָּם:
Ten generations from Adam until Noach. To apprise us how long-suffering He is. For all of these generations they kept on angering Him — until He brought upon them the waters of the flood. [You, too, do not wonder that He has been long-suffering to the idolators all of these years that they have been subjugating His children, for He was even more so to the idolators of the (ten) generations from Adam until Noach — until they were destroyed in the flood.] Ten generations from Noach until Abraham. To apprise us how long-suffering He is. For all of these generations they kept on angering Him — until Abraham came and took upon himself the reward of all. [He did good deeds corresponding to what all of them should have done — wherefore they were all rescued in his merit. And just as he took upon himself the yoke of mitzvoth in this world over and against all of them, so did he receive for the world to come reward over and against all of them. For every man has two shares, one in Gan Eden; the other, in Gehinnom. If he is meritorious, he takes his share and that of his neighbor (the evildoer) in Gan Eden. If he is culpable, he takes his share and that of his neighbor (the tzaddik) in Gehinnom.]