Musnad Ahmad 760:6

I read to Abd al-Rahman, Malik said: And Ishaq narrated to us, Malik informed me, from Zayd ibn Aslam, from Ata ibn Yasar, from Abdullah al-Sunabihi, who said: "When the servant performs wudu and rinses his mouth, the sins exit from his mouth. When he washes his face, the sins exit from his face until they exit from beneath his eyelashes. When he washes his hands, his sins exit from his hands until they exit from beneath his fingernails. When he wipes his head, the sins exit from his head until they exit from his ears. And when he washes his feet, the sins exit from his feet until they exit from beneath his toenails. Then, his walking to the mosque and his prayer are a supererogatory act for him."