Musnad Abu Ya'la al-Mawsili 115:118

Abu Yasir al-Mustamli narrated to us, Suwayd Abu Hatim al-Jahdari narrated to us, Qatadah narrated to us, from Anas, who said: We were with the Messenger of Allah, may Allah bless him and grant him peace, when a flea bit a man. He cursed it, so the Prophet, may Allah bless him and grant him peace, said: "Do not curse it, for it awakened a prophet among the prophets for prayer."