4:17. And Cain knew his wife, and she conceived, and brought forth Henoch: and he built a city, and called the name thereof by the name of his son Henoch.
His wife.... She was a daughter of Adam, and Cain’s own sister; God dispensing with such marriages in the beginning of the world, as mankind could not otherwise be propagated. He built a city, viz.... In process of time, when his race was multiplied, so as to be numerous enough to people it. For in the many hundred years he lived, his race might be multiplied even to millions.
4:18. And Henoch begot Irad, and Irad begot Maviael, and Maviael begot Mathusael, and Mathusael begot Lamech,
4:19. Who took two wives: the name of the one was Ada, and the name of the other Sella.
4:20. And Ada brought forth Jabel: who was the father of such as dwell in tents, and of herdsmen.
4:21. And his brother’s name was Jubal: he was the father of them that play upon the harp and the organs.
4:22. Sella also brought forth Tubalcain, who was a hammerer and artificer in every work of brass and iron. And the sister of Tubalcain was Noema.
4:23. And Lamech said to his wives Ada and Sella: Hear my voice, ye wives of Lamech, hearken to my speech: for I have slain a man to the wounding of myself, and a stripling to my own bruising.
I have slain a man, etc.... It is the tradition of the Hebrews, that Lamech in hunting slew Cain, mistaking him for a wild beast; and that having discovered what he had done, he beat so unmercifully the youth, by whom he was led into that mistake, that he died of the blows.
4:24. Sevenfold vengeance shall be taken for Cain: but for Lamech seventy times sevenfold.