Albert Barnes Commentary 1 Kings 13:11

"Now there dwelt an old prophet in Beth-el; and one of his sons came and told him all the works that the man of God had done that day in Beth-el: the words which he had spoken unto the king, them also they told unto their father." — 1 Kings 13:11 (ASV)

The truly pious Israelites left their homes when Jeroboam made his religious changes and, going to Jerusalem, strengthened the kingdom of Rehoboam (2 Chronicles 10:16–17). This “old prophet,” therefore, who had remained under Jeroboam without being infirm in any way and was even content to live at Bethel—the main center of the new worship—was devoid of any deep and earnest religious feeling.