You probably recall the story of Cain and Abel, how Cain, out of anger, rose up and killed his brother, thus providing our first recorded instance of murder (Genesis chapter 4). Cain was given a sign and promised that if anyone should kill him in retaliation, he will be avenged seven times over.
A few generations later, a descendant of Cain's, Lamech, is recorded as killing someone also.
Lamech said to his wives,I've always thought of Lamech as the typical bad-guy outlaw in Westerns, running rough-shod over other folks, and having a cocky "I run this town" attitude.
"Adah and Zillah, listen to me;
wives of Lamech, hear my words.
I have killed a man for wounding me,
a young man for injuring me.
If Cain is avenged seven times,
then Lamech seventy-seven times."
My cousin suggested otherwise; perhaps Lamech killed in self-defense, and he was merely saying, "A young man attacked me, and I killed him. If Cain is avenged seven-fold for murder, I should be avenged seventy-seven fold for self-defense."