Musnad Ahmad 1129:10

'Abd al-Samad narrated to us, Mulazim narrated to us, Hawdhah ibn Qays ibn Talq narrated to me, from his father, from his grandfather, who said: The Messenger of Allah (peace and blessings of Allah be upon him) used to perform the taslim to his right and to his left, until the whiteness of his right cheek and the whiteness of his left cheek could be seen.