Deuteronomy

And he that killeth any man shall surely be put to death.

The revenger of blood himself shall slay the murderer: when he meeteth him, he shall slay him.

Then tidings came to Joab: for Joab had turned after Adonijah, though he turned not after Absalom. And Joab fled unto the tabernacle of the Lord, and caught hold on the horns of the altar.

So Benaiah the son of Jehoiada went up, and fell upon him, and slew him: and he was buried in his own house in the wilderness.

Moreover thou knowest also what Joab the son of Zeruiah did to me, and what he did to the two captains of the hosts of Israel, unto Abner the son of Ner, and unto Amasa the son of Jether, whom he slew, and shed the blood of war in peace, and put the blood of war upon his girdle that was about his loins, and in his shoes that were on his feet.