Albert Barnes Commentary 2 Chronicles 22:10-12

"Now when Athaliah the mother of Ahaziah saw that her son was dead, she arose and destroyed all the seed royal 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 that were slain, and put him and his nurse in the 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. And he was with them hid in the house of God six years: and Athaliah reigned over the land." — 2 Chronicles 22:10-12 (ASV)

Compare the reference and notes in the margin.