"The Messenger of Allah ﷺ used to say the salam to his right so that the whiteness of his cheek could be seen, and to his left so that the whiteness of his cheek could be seen." (Using translation from Nasāʾī 1323)   

كَانَ رَسُولُ اللَّهِ ﷺ «يُسَلِّمُ عَنْ يَمِينِهِ حَتَّى يُرَى بَيَاضُ خَدِّهِ ثُمَّ يُسَلِّمُ عَنْ يَسَارِهِ حَتَّى يُرَى بَيَاضُ خَدِّهِ»  

[Machine] I prayed behind a man in Mecca and he performed two salaams. I mentioned that to Abdullah, and he said, "How did he end it?" The judge said, "The Prophet ﷺ used to do that."  

صَلَّيْتُ خَلْفَ رَجُلٍ بِمَكَّةَ فَسَلَّمَ تَسْلِيمَتَيْنِ فَذَكَرْتُ ذَلِكَ لِعَبْدِ اللَّهِ فَقَالَ «أَنَّى عَلِقَهَا؟» وَقَالَ الْحَكَمُ كَانَ النَّبِيُّ ﷺ يَفْعَلُ ذَلِكَ