Adam Clarke on 1 Kings 13:2

He cried against the altar - He denounced the destruction of this idolatrous system.

A child shall be born - Josiah by name - This is one of the most remarkable and most singular prophecies in the Old Testament. It here most circumstantially foretells a fact which took place three hundred and forty years after the prediction; a fact which was attested by the two nations. The Jews, in whose behalf this prophecy was delivered, would guard it most sacredly; and it was the interest of the Israelites, against whom it was levelled, to impugn its authenticity and expose its falsehood, had this been possible. This prediction not only showed the knowledge of God, but his power. He gave, as it were, this warning to idolatry, that it might be on its guard, and defend itself against this Josiah whenever a person of that name should be found sitting on the throne of David; and no doubt it was on the alert, and took all prudent measures for its own defense; but all in vain, for Josiah, in the eighteenth year of his reign, literally accomplished this prophecy, as we may read, 2Kgs 23:15-20. And from this latter place we find that the prophecy had three permanent testimonials of its truth.

1. The house of Israel;

2. The house of Judah; and,

3. The tomb of the prophet who delivered this prophecy, who, being slain by a lion, was brought back and buried at Beth-el, the superscription on whose tomb remained till the day on which Josiah destroyed that altar, and burnt dead men's bones upon it. See above, 2Kgs 23:16-18.