NET
15 But the Lord said to him, “All right then, if anyone kills Cain, Cain will be avenged seven times as much.” Then the Lord put a special mark on Cain so that no one who found him would strike him down.
Darby
15 And Jehovah said to him, Therefore, whoever slayeth Cain, it shall be revenged sevenfold. And Jehovah set a mark on Cain, lest any finding him should smite him.
KJV
15 And the LORD said unto him, Therefore whosoever slayeth Cain, vengeance shall be taken on him sevenfold. And the LORD set a mark upon Cain, lest any finding him should kill him.