Chaerephon was a dear friend of Socrates', though he had died prior to the trial. Socrates explains how it was Chaerephon who raised the question of Socrates' wisdom to the oracle of the god Apollo at Delphi. This man, not Socrates, was the one who asked the oracle "is there anyone wiser than Socrates?" The priestess-oracle serving Apollo told Chaerephon "No."
The Last Days of Socrates