Matthew Henry Commentary Genesis 4:19-24

"And Lamech took unto him two wives: the name of the one was Adah, and the name of the other Zillah. And Adah bare Jabal: he was the father of such as dwell in tents and [have] cattle. And his brother`s name was Jubal: he was the father of all such as handle the harp and pipe. And Zillah, she also bare Tubal-cain, the forger of every cutting instrument of brass and iron: and the sister of Tubal-cain was Naamah. 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 for wounding me, And a young man for bruising me: If Cain shall be avenged sevenfold, Truly Lamech seventy and sevenfold." — Genesis 4:19-24 (ASV)

One of Cain's wicked descendants is the first recorded as having broken the law of marriage. Until now, one man had only one wife at a time; but Lamech took two. Worldly things are the only things that carnal, wicked people set their hearts upon, and are most clever and industrious about.

So it was with this line of Cain. Here was a father of shepherds and a father of musicians, but not a father of the faithful. Here is someone to teach about brass and iron, but no one to teach the good knowledge of the Lord. Here are methods for how to be rich, how to be mighty, and how to be merry, but nothing of God, of His fear and service.

Present matters fill the minds of most. Lamech had enemies, whom he had provoked. He draws a comparison between himself and his ancestor Cain, and flatters himself that he is much less criminal. He seems to pervert God's patience in sparing Cain, turning it into an encouragement for himself to expect that he may sin without punishment.