Genesis 6:9

"In his generation..." - (Sanhedrin 109) Some of our rabbis interpret this as praise, meaning, all the more so, if he had been in a generation filled with righteous people, he would have been even more righteous. And there are those who interpret it as criticism, meaning, if he had been in Abraham's generation, he would not have been thought of as anything special.

"Noah walked with God..." - And with Abraham it says (Genesis 24): "Walk before Me!" Noah needed support to keep him up, but Abraham would strengthen himself and walk righteously on his own.

These are the genealogies of the race of Noah. Noah was a just man, complete in good works in his generation, (and) in the fear of the Lord walked Noah.

Righteous. In his deeds.

Flawless. In his heart.

In his generation (literally, “generations”). In the generation of the Flood and all the succeeding generations through which he lived. Noach did not die until Avraham was fifty-eight years old.

THESE ARE ‘TOLDOTH’ NOAH. Commentators to mean “progeny” or “generations” since it further states, And Noah begot three sons. have explained the word toldoth to mean “his experiences” [or “his events”] much the same as the sense of: what a day ‘yeiled’ (may bring forth).
In this way the word toldoth refers to the entire section [since all the events of the flood are occurrences in the life of Noah]. But this does not appear to me to be correct since the external events in the life of a person, [over which he has no control], are not his toldoth.
The correct interpretation is that the word toldoth here retains its literal meaning of “progeny,” just as, These are ‘toldoth’ (the progeny of) the sons of Noah; And these are ‘toldoth’ (the progeny of) Ishmael., 25:12. Thus Scripture is saying, “These are the progeny of Noah: Shem, Ham, and Japheth.”
Scripture however repeats, And Noah begot three sons, because [at the end of the first verse] it interrupted by saying, Noah was a righteous man, and whole-hearted, in order to inform us why He commanded him concerning the ark. And even though Scripture has already stated above, And Noah was five hundred years old; and Noah begot Shem, Ham, and Japheth, it returns to mention them a second time in order to relate that Noah was unlike all his ancestors who begot daughters and sons. This is the meaning of the words, three sons; Scripture mentions their number in order to say that these three alone were his progeny, and they were saved by his merit, and by them was the whole earth overspread.

אלה תולדות נח, his later descendants.

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

צדיק, in his deeds,

תמים, in his attitudes,

בדורותיו, 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.

את 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.

אלה תולדות נח, נח איש צדיק תמים היה בדורותיו, the meaning of the word תולדות is similar to “history of,” i.e. this it what happened to Noach, etc. It concerns both the deluge and what came after. We encounter the same pattern when the Torah introduced a paragraph with the words אלה תולדות יעקב, יוסף in Genesis 37,2 where this is an introduction to history related to Yaakov’s family. In Proverbs 27,1 we have a verse concluding with the words “the day will give birth to.” The root ילד is the root of the word תולדה and תולדות, i.e. it refers to future developments. Developments are matters that are the result of days following one another.

נח, the name occurs three times in the same verse, when a single mention of his name would have sufficed. In Numbers 8,19 the name בני ישראל occurs 5 times in one verse. According to Tanchuma 5 on our parshah such apparently needless repetitions are an expression of special affection by the writer for the subject described. Such formulations are referred to by Rashi in Numbers 8,19), as well as by Ibn Ezra as צחות הלשון, “stylistic purity.” [repeating Noach’s name 3 times indicates his popularity with G’d at that time. Ed.]

צדיק, his deeds all reflected fairness, charitable considerations, in contrast to those of his contemporaries who were men of violence.

תמים, perfect, without flaw; according to Tanchuma 5, he was born circumcised.

בדורותיו, both in the time of his generation, and the generation following him after the deluge. [this is the reason for the plural ending יו in the word בדורותיו. Ed.] Noach lived for 350 years after the deluge, so that he was a reminder of the deluge to at least 8-9 generations after him. In fact, Avraham was already 58 years old when Noach died, and he was the 10th generation counting from Noach. An easy way to remember this is the line that אברהם בן נח, “Avraham was a son of Noach“ (family member, as all people before the Torah was given) the numerical value of the letters in the name נח have a combined value of 58. According to Bereshit Rabbah 30,9 the word בדורותיו refers to three specific generations, that of Enosh, that of the deluge, and the generation of the Tower of Babel, and the scattering of mankind and the division into many languages.

אלה תולדת נח נח, “these are the generations of Noach, Noach;” why has the name of Noach been repeated here twice? He was exemplary vis a vis spiritual beings in the heavenly spheres as well as vis a vis his contemporaries on earth. (B’reshit Rabbah, 30,4) The meaning is to tell us that whenever we encounter such a construction of a person’s name appearing twice in a row, it is to remind us that the person concerned was a righteous person. An example for this is found in Genesis 2,11, where the name Avraham appears twice in a row. This interpretation has been challenged in the Jerusalem Talmud where it is pointed out that we find the same repetition of a man’s name applied to Avraham’s father Terach, a renowned idolater and seller of heathen images (Genesis 11,27) The answer provided by B’reshit Rabbah is that Terach, though an idolater had become a penitent. It is this very fact that convinced our sages that he had become a penitent before his death. This also explains why Avraham was told by G–d in Genesis 15,15, that he would join his fathers in the hereafter.