Amir bin Sa'd narrates from his father (may Allah be pleased with him) that he said: I used to see the Messenger of Allah (peace and blessings be upon him) giving the salam to his right and to his left, until I could see the whiteness of his cheek.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2979