(ט) אֵ֚לֶּה תּוֹלְדֹ֣ת נֹ֔חַ נֹ֗חַ אִ֥ישׁ צַדִּ֛יק תָּמִ֥ים הָיָ֖ה בְּדֹֽרֹתָ֑יו אֶת־הָֽאֱלֹהִ֖ים הִֽתְהַלֶּךְ־נֹֽחַ׃
(9) This is the line of Noah.—Noah was a righteous man; he was blameless in his age; Noah walked with God.
(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) 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).
Rashi (Rabbi Shlomo Yitzhak) lived in France, 1040-1105
(1) Righteous. In his deeds.
(2) Flawless. In his heart.
(3) In his generation (literally, “generations”). In the generation of the Flood and all the succeeding generations through which he lived.
Abraham Ibn Ezra lived in Spain, 1089-1167
HE WAS A RIGHTEOUS MAN AND WHOLE-HEARTED. Scripture mentions that he was guiltless and perfect in his righteousness in order to inform us that he was worthy to be saved from the flood without any punishment whatever since he was whole-hearted in righteousness. For a tzadik (a righteous person) is one who is found guiltless in judgment as opposed to the wicked person. Now after Scripture said that Noah was a righteous man, meaning that he was neither a man of violence nor one who perverted his ways as did the guilt ones in his generation, it further said that he walked with the glorious Name, fearing God alone. He was not enticed by astrologers, enchanters and soothsayers, and surely not idolatry, and he paid no heed to them at all; to God alone did he cleave, and he walked in the way God chose or taught him after he was a prophet. Now since Noah was a righteous man and undeserving of punishment, it was fitting that his sons and his household be saved by his merit for if his sons were to perish, it would have been a punishment upon him. Or it may be said that he was a perfectly righteous man, and his sons and household were also righteous since he taught them.
IN HIS GENERATIONS. The correct interpretation according to the plain meaning of Scripture appears to be that he alone was a righteous man in those generations, there being no righteous or whole-hearted men except him in those generations.
Rambam (Rabbi Moshe ben Nachman) lived in Catalonia, 1194-1270
(1) תולדות נח, a reference to his history, commencing with his own life and continuing with that of his offspring.
(2) צדיק, in his deeds,
(3) תמים, in his attitudes, בדורותיו, according to the generations during which he lived.
(4) את האלוקים התהלך נח, he walked in God’s way trying to be helpful to others, and to instruct and if necessary to rebuke them, as our sages pointed out.
Obadiah ben Yaakov Sforno lived in Italy, 1475-1550