"And Lamech said to his wives" (Genesis 4:23). The wives saw that they had fulfilled "be fruitful and multiply" — Adah had borne two sons, and Zillah had borne a son and a daughter — so they separated from their husbands. They said: Why should we give birth in vain? For our building lasts only until seven generations, and the Lord has decreed that the seed of Cain shall not endure. And when Lamech saw that they would not listen to him to join with him, he began to say: "I have slain a man for wounding me, and a child for bruising me" — for did I slay Abel, who was a great man like other men, and a child, in the two of whom, by reason of that sin, his seed shall be suspended? For Cain, who slew him, judgment was suspended for seven generations; and for me, who did not slay him, shall not the Holy One, blessed be He, suspend it until seventy and seven generations?
Another interpretation. According to the one who says that he had a horn on his forehead, and they said to Lamech that he had slain Cain — and therefore his wives separated from him: For Lamech was blind, and Tubal-cain would lead him; and Lamech would shoot with the bow and hunt wild beasts. For when Tubal-cain would see, he would say to Lamech, "I see a beast," and Lamech would say to him, "In what place is it?" and he would show him, and Lamech would shoot with the bow and slay it. Once Lamech went out to hunt, and Tubal-cain did not know Cain, that he had a single horn on his forehead. He said to Lamech his father, "I see the likeness of a beast in such-and-such a place." Lamech drew the bow and struck Cain and slew him. When they went over to him, Tubal-cain said to Lamech his father: "You have not slain a beast, but Cain our ancestor you have slain, who had a horn on his forehead." When he heard this — and he was blind — he struck his hands one against the other, palm against palm, and slew Tubal-cain his son between his two hands. And therefore they separated from him. They said to him: "You have slain Cain our ancestor, and you have also slain Tubal-cain our son; we will not listen to you."
And therefore he said: "I have slain a man for wounding me, and a child for bruising me" — this is Cain, whom I did not slay deliberately, just as Cain did, who slew Abel his brother with wounds and bruises deliberately. If for Cain, who slew his brother deliberately, the Holy One, blessed be He, suspended for him seven generations, then for me, who slew only inadvertently, how much the more so that He should suspend for me seventy and seven generations! They said to him: "We will not listen to you." He said to them: "Let us go to Adam the first man; if he says that you should separate from me for what I have done, then you shall be exempt." Immediately they went to Adam the first man. He said to them: "If the Holy One, blessed be He, exacts His judgment from Cain, what is it to you? Return to your husbands, and what the Holy One, blessed be He, wishes to do, He will do." The women said to him: "Physician, gird your own girdle! Did you not yourself separate from your wife a hundred and thirty years because death was decreed upon you? Why should we not separate from our husband, who slew Cain our ancestor and Tubal-cain our son? If you wish that we return to our husbands, return you first to your wife, and after you we will learn from you to return to Lamech our husband." Adam said to them: "Learn from me, and so shall you do." Immediately Adam returned to his wife. This is what is written: "And Adam knew [again] his wife" (Genesis 4:25).