“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.”
King James Version (KJV)
4:15 Whosoever slayeth Cain vengeance shall be taken on him seven - fold - God having said in Cain's case Vengeance is mine, I will repay; it had been a daring usurpation for any man to take the sword out of God's hand. And the Lord set a mark upon Cain - To distinguish him from the rest of mankind. What the mark was, God has not told us: therefore the conjectures of men are vain.