But 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 a 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 slew him not. (2 Chronicles 22:11)
This information is not found in Kings. The fact that Jehoshabeath was the wife of Jehoiada the priest helps to explain her loyalty to the seed of David and also shows how she was in a position to hide the infant prince for so long a time.