2SA 17:23

23 When Ahithophel realized that Absalom was not going to do what he suggested, he put a saddle on his donkey and returned to his own town. He gave [to his family] instructions about his possessions, and then he hanged himself [because he knew that Absalom would be defeated and that he would be considered a traitor and be killed]. His body was buried in the tomb where his ancestors [had been buried].