Musnad Ahmad 962:138

Yahya ibn Abi Bukayr and Abu Sa’id narrated to us, they said: Za’idah narrated to us, ‘Asim ibn Abi al-Najud narrated to us, from Shahr ibn Hawshab, from Abu Umamah, who said: If I had not heard it from the Prophet, may Allah bless him and grant him peace, seven times—Abu Sa’id said: nine times—I would not have narrated it. He said: "When a man performs wudu as he was commanded, the sin departs from his hearing, his sight, his hands, and his feet."