2 Chronicles 24:22
Thus Joash the king remembered not the kindness which Jehoiada his father had done to him, but slew his son. And when he died, he said, The LORD look upon it, and require it. Thus Joash the king remembered not the kindness which Jehoiada his father had done to him, but slew his son. And when he died, he said, The LORD look upon it, and require it.
Joash did not remember the kindness which Jehoiada had done for him, but repaid that kindness with ingratitude by having Jehoiada's son put to death. The son was Zechariah the prophet, who was slain while delivering God's warning. He was killed as he reproved the king and the people for forsaking God.
When dying he said that the Lord should look upon the deed and require it, asking God to see it and to exact justice for it. His blood thus remained as a witness against apostate Israel, crying out to God for justice for silencing God's messenger. Jesus used this murder to warn that the generation that rejected Him would bear responsibility for the blood of the righteous shed from Abel to Zechariah. The account shows that people who condemn their ancestors for killing the prophets may cherish the same spirit and repeat the same crime when they themselves are reproved.