Wikipedia
Hushai
Hushai (hus'-sha-i) or Chusai was a friend of David and a spy according to the Hebrew Bible. During Absalom's rebellion described in the Second Book of Samuel, he agrees to act as an advisor to Absalom to sabotage his plans while secretly sending information to David. It was on his advice that Absalom did not immediately pursue the retreating David, thus giving David time to regroup and gather his forces. Hushai's advice helped to ensure Absalom's rapid defeat.