Musannaf Ibn Abi Shayba 1:46

Waki’ narrated to us, from Mis’ar, from Abu Sakhr (Sakhr), he said: I heard Humran say: I used to place the water for purification for Uthman. He said: The Messenger of Allah (may Allah bless him and grant him peace) narrated to us: "There is no man who performs ablution and perfects the ablution, except that what is between it and the other prayer is forgiven for him."