While Absalom was offering the sacrifices, he sent for Ahithophel the Gilonite, David’s counselor, to come from his hometown of Giloh. So the conspiracy gained strength, and Absalom’s following kept increasing.
Jewish Publication Society of America Version (JPS1917) - 2 Samuel 15:12 >And Absalom sent for Ahithophel the Gilonite, David's counsellor, from his city, even from Giloh, while he offered the sacrifices. And the conspiracy was strong; for the people increased continually with Absalom.