'Reign' in the Bible

Ishbosheth Saul's son was forty years old when he began to reign over Israel, and reigned two years. But the house of Judah followed David.

And Abner said unto David, I will arise and go, and will gather all Israel unto my lord the king, that they may make a league with thee, and that thou mayest reign over all that thine heart desireth. And David sent Abner away; and he went in peace.

David was thirty years old when he began to reign, and he reigned forty years.