Musannaf Ibn Abi Shayba 3:28

Abu Bakr narrated to us, he said: Ubaydullah narrated to us, he said: Isra'il narrated to us, from Abu Ishaq, from Abdullah ibn Abi al-Khalil, from Ali, he said: I heard him when he said the takbir in the prayer, he said: "There is no god but You, glory be to You. I have wronged my soul, so forgive me my sins, for indeed, no one forgives sins except You."