Charles Ellicott Commentary 2 Samuel 17:23

"And when Ahithophel saw that his counsel was not followed, he saddled his ass, and arose, and gat him home, unto his city, and set his house in order, and hanged himself; and he died, and was buried in the sepulchre of his father." — 2 Samuel 17:23 (ASV)

And hanged himself. —Ahithophel was moved, not merely by chagrin at the rejection of his counsel, but was shrewd enough to see that, with this delay, Absalom’s rebellion would inevitably fail, and he himself be likely to come to a traitor’s death.