In Genesis 4, 23-24, Lamech sings:

23 Lamech said to his wives:
“Adah and Zillah, hear my voice;
you wives of Lamech, listen to what I say:
I have killed a man for wounding me,
a young man for striking me.
24 If Cain’s revenge is sevenfold,
then Lamech’s is seventy-sevenfold.”

Drysdale makes the following observation on Lamech:

Lamech, the first polygamist on record, the first notorious violator of the primitive marriage law and family constitution, goes early in the ‘way of Cain,’ and becomes, by his own confession, in intent, if not also in fact, a homocide. Polygamy seems never far from bloodshed. Sin cannot live single. It mates with misery, and both breed their like again, in aggravated form. A breach of the Seventh Commandment is twin-brother with a breach of the Sixth. They are children that go hand in hand. He who speaks to his ‘wives’ is he who speak, or rather singsfamiliarly of ‘slaying a man.’

A.H. Drysdale Early Bible Song, “The Song of the Sword,” TheReligious Tract Society, Piccadilly: 1890; p. 155