2 Samuel 17:23 (KJV)

And it came to pass, after they were departed, that they came up out of the well, and went and told king David, and said unto David, Arise, and pass quickly over the water: for thus hath Ahithophel counselled against you.

Then David arose, and all the people that were with him, and they passed over Jordan: by the morning light there lacked not one of them that was not gone over Jordan.

And when Ahithophel saw that his counsel was not followed, he saddled his ass, and arose, and gat him home to his house, to his city, and put his household in order, and hanged himself, and died, and was buried in the sepulchre of his father.

Then David came to Mahanaim. And Absalom passed over Jordan, he and all the men of Israel with him.

And Absalom made Amasa captain of the host instead of Joab: which Amasa was a man’s son, whose name was Ithra an Israelite, that went in to Abigail the daughter of Nahash, sister to Zeruiah Joab’s mother.