Musnad Abu Ya'la al-Mawsili 115:13

'Abd al-Wahid narrated to us, Abu 'Awanah narrated to us, from Qatadah, from Anas, from the Prophet (may Allah bless him and grant him peace), who said: "Whoever forgets a prayer, let him pray it when he remembers it." Khalaf ibn Hisham narrated to us, with his chain of narration, the like of it.