The Messenger of Allah ﷺ used to give the salutation in his prayer to his right and to his left until the whiteness of his cheeks could be seen.
حدثنا يحيى بن إسحاق أخبرنا ابن لهيعة عن محمد بن عبد الله بن مالك عن سهل بن سعد الأنصاري
أن رسول الله ﷺ كان يسلم في صلاته عن يمينه وعن يساره حتى يرى بياض خديه
Its chain is sahih. Muhammad bin Abdullah bin Malik Dar Madani was a trustworthy Tabii, mentioned by Ibn Hibban in Thiqat, and Bukhari gave his biography in Kabir 1/1/127-128, saying that he heard from Umm Salama. Sahl bin Saad Saadi Ansari was a well known companion, born five years before the Hijrah, and he died after reaching the age of 100 or more. The hadith is an abridgment of 3888.