2 Kings 11:3

And when Athaliah the mother of Ahaziah saw that her son was dead, she arose and destroyed all the seed royal.

But Jehosheba, the daughter of king Joram, sister of Ahaziah, took Joash the son of Ahaziah, and stole him from among the king's sons which were slain; and they hid him, even him and his nurse, in the bedchamber from Athaliah, so that he was not slain.

And the seventh year Jehoiada sent and fetched the rulers over hundreds, with the captains and the guard, and brought them to him into the house of the LORD, and made a covenant with them, and took an oath of them in the house of the LORD, and shewed them the king's son.

And he commanded them, saying, This is the thing that ye shall do; A third part of you that enter in on the sabbath shall even be keepers of the watch of the king's house;