Musannaf Ibn Abi Shayba 1:52

Qabisah ibn Uqbah narrated to us, from Hammad ibn Salamah, from Ali ibn Zayd, from Abu Uthman, who said: I was with Salman, and he took a branch from a dry tree and shook it, then he said: I heard the Messenger of Allah, may Allah bless him and grant him peace, say: "Whoever performs ablution and perfects the ablution, his sins fall away just as these leaves fall away."