Musnad Ahmad 30:1438

'Affan narrated to us, Abu 'Awanah narrated to us, from Dawud ibn 'Abdullah al-Awdi, from Humayd ibn 'Abd al-Rahman al-Himyari, from Abu Hurayrah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said—or Abu al-Qasim (peace and blessings of Allah be upon him) said: "Let not one of you urinate in standing water, then perform ghusl (full ablution) from it."