II Chronicles 22:10-12

Now when Athaliah the mother of Ahaziah saw that her son was dead, she arose and destroyed all the royal heirs of the house of Judah. But Jehoshabeath, the daughter of the king, took Joash the son of Ahaziah, and stole him away from among the king’s sons who were being murdered, and put him and his nurse in a bedroom. 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 kill him. And he was hidden with them in the house of God for six years, while Athaliah reigned over the land.