Genesis 5:26

“And Methuselah lived, after he begat Lamech, seven hundred eighty and two years, etc.] The Greek version is eight hundred and two years, and so makes the sum total of his life the same; but the Samaritan version only six hundred and fifty three, and so makes his whole life but seven hundred and twenty; and thus, instead of being the oldest, he is made the youngest of the antediluvian patriarchs, excepting his father Enoch: and begat sons and daughters; some, it is highly probable, before he beget Lamech, since then he was near two hundred years of age, as well as others after.”

“Lamech--a different person from the one mentioned in the preceding chapter [Gen 4:18]. Like his namesake, however, he also spoke in numbers on occasion of the birth of Noah--that is, "rest" or "comfort" [Gen 5:29, Margin]. "The allusion is, undoubtedly, to the penal consequences of the fall in earthly toils and sufferings, and to the hope of a Deliverer, excited by the promise made to Eve. That this expectation was founded on a divine communication we infer from the importance attached to it and the confidence of its expression" [PETER SMITH].”

“- Section V - The Line to Noah - The Line of Sheth 1. ספר sepher “writing, a writing, a book.” 9. קינן qēynān, Qenan, “possessor, or spearsman.” 12. מהללאל mahelal'ēl, Mahalalel, “praise of ‘El.” 15. ירד yerĕd, Jered, “going down.” 21. מתוּשׁלה metûshālach, Methushelach, “man of the missile.” 29. נה noach, Noach, “rest,” נחם nācham “sigh; repent; pity; comfort oneself; be revenged.” 32. שׁם shēm, Shem, “name, fame; related: be high.” חם chām Cham, “hot.” יפת yāpet, Japheth, “spreading; related: spread out.” We now enter upon the third of the larger documents contained in Genesis. The first is a diary, the second is a history, the third a genealogy. The first employs the name אלהים…”

“begat sons: Gen 5:4 Genesis 5:27”