Majma al-Zawaid — Hadith 2754

Sayyiduna Adi bin Amirah al-Hadrami (may Allah be pleased with him) said: When the Prophet (peace and blessings be upon him) went into prostration, the whiteness of his armpits could be seen. When he gave the salam, he would turn his face fully to the right until the whiteness of his cheek could be seen, and then to the left as well (giving the salam in the same way).
Imam al-Tabarani recorded it in al-Mu'jam al-Awsat as a lengthy narration, and in al-Mu'jam al-Kabir in abridged form, mentioning the giving of the salam; the narrators of al-Awsat are thiqat (trustworthy).