Who told saul that david had visited ahimelech?

Doeg the Edomite informed Saul that David had visited Ahimelech, the priest at Nob. In 1 Samuel 21 and 22, Doeg witnessed David receiving provisions and Goliath's sWord from Ahimelech and later reported this to Saul, leading to dire consequences for Ahimelech and the priests at Nob.