Who told caesar about the Ides of March?

In the play "Julius Caesar" by William Shakespeare, it is the soothsayer who warns Caesar to beware of the Ides of March. The Ides of March refers to the 15th day of March in the Roman calendar. In the play, the soothsayer encounters Caesar on his way to the Senate and utters the famous line, "Beware the Ides of March." This warning foreshadows Caesar's assassination, which takes place on that very day.