Musnad Ahmad 536:11

'Ali ibn 'Abdullah narrated to us, Mu'tamir ibn Sulayman narrated to us, he said: I read to al-Fudayl ibn Maysarah, he said: Abu Hurayz narrated to me, that Qays ibn Abi Hazim narrated to him, that 'Adi ibn 'Amirah said: "When the Prophet, peace and blessings of Allah be upon him, would prostrate, the whiteness of his armpits could be seen. Then, when he would perform the taslim, he would turn his face to his right until the whiteness of his cheek could be seen, then he would perform the taslim to his left and turn his face until the whiteness of his cheek could be seen on his left."