2 Chronicles 22:10-11

10And when Athaliah the mother of Ahaziah saw that her son was dead, she rose up and exterminated all the royal seed of the house of Judah.

11But Jehoshabeath the daughter of the king took Joash the son of Ahaziah and stole him from among the king's sons that were slain, and put him and his nurse in the bedchamber. So Jehoshabeath, the daughter of king Jehoram, the wife of Jehoiada the priest (for she was the sister of Ahaziah), hid him from Athaliah, so that she did not slay him;