2 Chronicles 22:9-13

He also searched for Ahaziah, and they caught him while he was hiding in Samaria; they brought him to Jehu, put him to death, and buried him. For they said, “He is the son of Jehoshaphat, who sought the Lord with all his heart.” So there was no one of the house of Ahaziah to retain the power of the kingdom.

Now when Athaliah the mother of Ahaziah saw that her son was dead, she rose and eliminated all the royal children of the house of Judah.

But Jehoshabeath the king’s daughter took Joash the son of Ahaziah, and stole him from among the king’s sons who were being put to death, and placed him and his nurse in the 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 would not put him to death.

He kept himself hidden with them in the house of God for six years while Athaliah reigned over the land.