2 Chronicles 22:10-12

10Now when Athaliah the mother of Ahaziah saw that her son was dead, she rose and destroyed all the royal family of the house of Judah.

11But Jehoshabeath, the king’s daughter, took Joash the [infant] son of Ahaziah and stole him away from among the king’s sons who were being put to death, and she placed him and his nurse in the bedroom. So Jehoshabeath, the daughter of King Jehoram [of Judah] and wife of Jehoiada the priest, hid Joash from [his grandmother] Athaliah so that she did not murder him (for Jehoshabeath was the sister of Ahaziah).

12Joash was hidden with them in the house (temple) of God for six years, and Athaliah reigned over the land.