Musnad Ahmad 25:1591

'Abd al-Razzaq narrated to us, Sufyan informed us, from Zayd ibn Aslam, from 'Ata' ibn Yasar, from Ibn 'Abbas, who said: "Shall I not inform you of the ablution of the Messenger of Allah, may Allah bless him and grant him peace?" He called for water, then he began to scoop with his right hand, then he poured it onto his left.