Lamech is mentioned in Genesis 4:19-24. Lamech is a very misunderstood man.
Genesis 4:23-24 “And Lamech said unto his wives, Adah and Zillah, Hear my voice; ye wives of Lamech, hearken unto my speech: for I have slain a man to my wounding, and a young man to my hurt. If Cain shall be avenged sevenfold, truly Lamech seventy and sevenfold.”
We learn from an extra Biblical source a little more about what happened.
Jasher 2:26-31 And Lamech was old and advanced in years, and his eyes were dim that he could not see, and Tubal Cain, his son, was leading him and it was one day that Lamech went into the field and Tubal Cain his son was with him, and whilst they were walking in the field, Cain the son of Adam advanced towards them; for Lamech was very old and could not see much, and Tubal Cain his son was very young. And Tubal Cain told his father to draw his bow, and with the arrows he smote Cain, who was yet far off, and he slew him, for he appeared to them to be an animal. And the arrows entered Cain’s body although he was distant from them, and he fell to the ground and died. And the Lord requited Cain’s evil according to his wickedness, which he had done to his brother Abel, according to the word of the Lord which he had spoken. And it came to pass when Cain had died, that Lamech and Tubal went to see the animal which they had slain, and they saw, and behold Cain their grandfather was fallen dead upon the earth. And Lamech was very much grieved at having done this, and in clapping his hands together he struck his son and caused his death.
Lamech’s wives separated from him because of this, but they later returned to him at the advice of Adam.
Many disregard this source because it isn’t scripture. They are correct it is not scripture, but it is information. Those same people who reject this will pick up any number of other various sources and have no problem believing what they print. They are also not scripture. Perhaps we should consider that God has preserved the Book of Jasher for our benefit? What other book can you think of that we have that scripture tells us to look at?