Musannaf Ibn Abi Shayba 27:152

Ibrahim ibn al-Awwam narrated to us, he said: A man from Banu Asad narrated to me, from Abdullah ibn Umar, that he said: Whoever invokes blessings upon the Prophet, may Allah bless him and grant him peace, ten good deeds are written for him, ten evil deeds are removed from him, and ten degrees are raised for him.