2 Kings 8:26

Two and twenty years old was Ahaziah when he began to reign,
&c.] In ( 2 Chronicles 22:2 ) he is said to be forty two years of age; for the solution of that difficulty (See Gill on 2 Chronicles 22:2):

and he reigned one year in Jerusalem;
which was the whole of his reign:

and his mother's name was Athaliah the daughter of Omri king of Israel;
that is, his granddaughter; for she was the daughter of Ahab the son of Omri, ( 2 Kings 8:18 ) , it was usual for grandchildren to be called children, sons and daughters, and perhaps she might be educated in the family of Omri.