Musannaf Ibn Abi Shayba 1:43

Ghundar narrated to us, from Shu'bah, from Ya'la ibn 'Ata, from Yazid ibn Talq, from 'Abd al-Rahman ibn al-Baylamani, from 'Amr ibn 'Abasah, from the Prophet (peace be upon him), who said: "When the servant performs ablution and washes his hands, his sins exit from his forearms. And when he wipes his head, his sins exit from his head. And when he washes his feet, his sins exit from his feet."