§ 02 · King James Bible
Genesis 4:15
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.
Simple English
So God told Cain, whoever kills you will be punished even more. God also put a special mark on Cain to protect him from being killed.
* Work in progress - there may be occasional inaccuracies