It is narrated from Sayyiduna Wa'il bin Hujr (may Allah be pleased with him) that he heard the Messenger of Allah (peace and blessings be upon him), when he recited "Not of those who have earned anger, nor of those who go astray" [Surah al-Fatihah: 7], say: "My Lord, forgive me. Amin."
Hadith Referenceالمعجم الكبير للطبراني / باب الواو / 18327