You know the rest of the history, how Absalom took the advice of Hushai, and Ahithophel was defeated. God does not always answer prayer quite as ra…

Behold, [they have] there with them two sons, Ahimaaz, Zadok's
[son], and Jonathan, Abiathar's [son]…

David prays not against Ahithophel's person, but against his counsel. He prayed this, in firm belief that God has all hearts in His hand, and tongu…