Musannaf Ibn Abi Shayba 3:664

Muhammad ibn Bishr al-‘Abdi narrated to us, he said: Muhammad ibn ‘Amr narrated to us, from Mus’ab ibn Thabit, from Isma’il ibn Muhammad, from ‘Amir ibn Sa’d, from Sa’d, who said: The Messenger of Allah (may Allah bless him and grant him peace) used to perform the taslim to his right and to his left, until the whiteness of his cheek could be seen.