'Be Merciful' in the Bible

Be merciful, O LORD, to thy people Israel, whom thou hast redeemed, and lay not innocent blood to the charge of thy people Israel. And the blood shall be forgiven them.

Rejoice, O ye nations, with his people: for he will avenge the blood of his servants, and will render vengeance to his adversaries, and will be merciful to his land, and to his people.