The altar also was rent, and the ashes poured out from the altar, according to the sign which the man of God had given by the word of the Lord. (1 Kings 13:5)
This manifestation of the Lord’s presence and power was something that could not be successfully gainsaid. Instead of being persuaded of the solemnity of the altar and the sanctity of their priestly king, the people now realized that Jeroboam was acting in direct defiance of Heaven and bringing upon himself the divine rebuke.