2 Samuel 15:10-12

But Absalom sent spies throughout all the tribes of Israel, saying, As soon as ye hear the sound of the trumpet, then ye shall say, Absalom is king in Hebron. And with Absalom went two hundred men out of Jerusalem, that were invited, and went in their simplicity; and they knew not anything. And Absalom sent for Ahithophel the Gilonite, David’s counsellor, from his city, even from Giloh, while he was offering the sacrifices. And the conspiracy was strong; for the people increased continually with Absalom.