Dora Bas Rivka Silver O'H
Lemech called his wives to tell them that he had accidentally killed both a man and a boy. (According to tradition, he had killed his ancestor Cain and his son, Tuval Kayin.) If Cain would be avenged seven times, Lemech said, then surely he would be avenged 77 times! (An alternative reading of 4:15 is that Cain would die after seven generations, which we see he did. According to this interpretation, Lemech is saying that, since he killed accidentally, his sentence should be suspended for 77 generations.)
Meanwhile, Adam and Eve had another son, whom they named Seth (“Shais” in Hebrew). Shais had a son named Enosh, during whose lifetime idolatry started.
The Torah now lists the generations of Adam’s descendants, indicating how long each one lived and the age at which they had children. (This makes it child’s play to calculate the timing of various events relative to the creation of the world.) Among the more notable of Adam’s descendants was Chanoch (a descendant of Seth, not the son of Cain). Chanoch was so righteous that G-d took him into Heaven alive, before he could become corrupted by others’ evil influence.