2 Samuel 15:12, 31

While Absalom was offering sacrifices, he also sent for Ahithophel the Gilonite, David’s counselor, to come from Giloh, his hometown. And so the conspiracy gained strength, and Absalom’s following kept on increasing.

Now David had been told, “Ahithophel is among the conspirators with Absalom.” So David prayed, “LORD, turn Ahithophel’s counsel into foolishness.”