John Gill Commentary 1 Kings 13:31

"And it came to pass, after he had buried him, that he spake to his sons, saying, When I am dead, then bury me in the sepulchre wherein the man of God is buried; lay my bones beside his bones." — 1 Kings 13:31 (ASV)

And it came to pass, after he had buried him, that he spoke to
his sons, saying
He gave them the following charge:

when I am dead, then bury me in the sepulchre wherein the man of God is
buried ;
as it was his own, it might be reasonably thought they would bury him in it without such a charge; but, lest they should not, he gives it:

lay my bones beside his bones ;
his view in this was, that when Josiah came to burn the bones of the priests, he would spare the bones of this man of God; and so his, lying by them, and mingled with them, would be spared also, and so it proved, (2 Kings 23:18) .