Musnad Abu Ya'la al-Mawsili 116:39

Ahmad narrated to us, Shababa narrated to us, Shu'bah narrated to us, from Qatadah, from Anas, who said: "Indeed, We have given you a clear conquest" was revealed to the Messenger of Allah, may Allah bless him and grant him peace, when he returned from al-Hudaybiyyah.