And he gave a sign the same day, saying, this is the sign
 which the Lord hath spoken
 As a confirmation of the truth of what the prophet had said, and for the proof of his being a true prophet of the Lord: 
 behold, the altar shall be rent;
 of itself, by an invisible hand, by the power of God: 
 and the ashes that are upon it shall be poured out;
 signifying it should be entirely demolished, not only shaken but destroyed, so as not to be capable of retaining the ashes on it; this was an emblem of the utter abolition of idolatry here in future times.