What does Genesis 4:23 mean?

Lamech, six generations removed from Cain, demonstrates that he shared Cain's anger, violence, and arrogance—and then some. In this speech, continuing into the following verse, he brags about his sin in an almost unbelievable way.

He announces to his two wives that he has killed a man in revenge for wounding and/or striking him. We obviously don't know the whole story. However, Lamech's response indicates that his action was out of proportion with what was done to him. The Hebrew word used for "kill" here is from the root word hā'rag, the same used to describe the murder of Abel in Genesis 4:8 and Moses' murder of the Egyptian in Exodus 2:14.

He sounds proud and arrogant, and even more so in light of the following verse. The fact that he specifically directs this confession of murder to his wives can be interpreted in several ways. One prominent possibility is that this is meant to be a threat: "look what happens to people who cross me."