Musnad Ahmad 25:1606

'Abd al-Razzaq and Ibn Bakr narrated to us, they said: Ibn Jurayj informed us, he said: 'Amr ibn Dinar informed me, and he said: "My knowledge, and what comes to my mind, is that Abu al-Sha'tha' informed me that Ibn 'Abbas informed him: 'That the Prophet, peace and blessings of Allah be upon him, used to perform ghusl with the remaining water of Maymunah.'" 'Abd al-Razzaq said: "And that is because I asked him about emptying both sides together."