זה ספר תולדות אדם THIS IS THE BOOK OF THE GENERATIONS OF ADAM — This is the record (or, enumeration) of the generations of Adam. There are however, many Midrashic observations on this verse

‘ביום ברא וגו IN THE DAY THAT [GOD] CREATED etc. — This states that on the day when he was created he begot progeny (Genesis Rabbah 24:7).

שלשים ומאת שנה A HUNDRED AND THIRTY YEARS — Until then he lived apart from his wife (Genesis Rabbah 24:6).

ויתהלך חנוך AND ENOCH WALKED [WITH GOD] — He was a righteous man, but his mind was easily induced) to turn from his righteous ways and to become wicked. The Holy One, blessed be He, therefore took him away quickly and made him die before his full time. This is why Scripture uses a different expression when referring to his death by writing ואיננו “and he was not”, meaning, he was not in the world to complete the number of his years.

כי לקח אותו FOR GOD TOOK HIM — before his time; a similar meaning of לקח “to take” we find in (Ezekiel 24:16), “I take away from thee the desire of thine eyes [by a plague]”.

ויולד בן AND HE BEGOT A SON (בן “son”, connected with the root בנה ‘‘to build”) — from whom the world was built up (peopled) (Tanchuma 1:1:11)

זה ינחמנו THIS WILL COMFORT US — He will ease from off us (ינחמנו) the toil of our hands. For until Noah came people had no agricultural instruments and he prepared such for them. The earth had brought forth thorns and thistles when they sowed wheat in consequence of the curse imposed upon Adam Harishon: in the days of Noah, however, this ceased (Tanchuma 1:1:11). This is what is meant by the word ינחמנו (viz., ינח מנו). If, however, you do not explain it in this manner, but from the root נחם “to comfort”, then the meaning you give to this expression (connecting it with the idea of “comfort”) will have no application to the name נח, and you would have to call him מנחם “Comforter”.

בן חמש מאות שנה FIVE HUNDRED YEARS OLD — R. Judan said: “How is it that all the previous generations had children at the age of hundred years and this one (Noah) at the age of 500 years? The Holy One, blessed be He, said, “If they (Noah’s children) be wicked, they will perish by the water of the Flood and it will grieve this righteous man; if they be righteous, I shall have to trouble him to construct several arks.” He therefore restrained him from having children until he was 500 years old, in order that Japhet, the oldest of his sons (cf. Rashi on Genesis 10:21) should not reach the punishable age before the Flood. For it is written (Isaiah 65:20), “For as a lad shall one die when he is one hundred years old”, meaning, that in the future time, he will only then be of punishable age, and this was so, too, before the giving of the Torah (Genesis Rabbah 26:2) .

את שם ואת חם ואת יפת SHEM, HAM AND JAPHETH — But was not Japheth the eldest? But you naturally first interest yourself in Shem who was a righteous man, who was born circumcised (a sign of righteousness) and from whom Abraham was to descend (Genesis Rabbah 26:3).