'Seven fold' in the Bible

And the Lord said to him, “Therefore, whoever kills Cain, a sevenfold vengeance [that is, punishment seven times worse] shall be taken on him [by Me].” And the Lord set a [protective] mark (sign) on Cain, so that no one who found (met) him would kill him.

“If Cain is avenged sevenfold [as the Lord said he would be],Then Lamech [will be avenged] seventy-sevenfold.”