Musannaf Ibn Abi Shayba 3:5269

Yazid ibn Harun narrated to us, [he said] Awf and al-Jariri informed us, from Qasama ibn Zuhayr, from Abu Musa, who said: The likeness of the five prayers is like a flowing river at the door of one of you, in which he bathes five times every day. So what remains of his filth after that?