The first Salām is a pillar of prayer and the second is recommended. The Prophet (May Allāh praise him and Peace be upon him) used to say Salām (Al Salāmu ‘alaikum wa raḥmatullāh) on his right side such that the white of his right cheek could be seen and would give Salām (Al Salāmu ‘alaikum wa raḥmatullāh) on his left side such that the white of his left cheek could be seen. [Reported by Muslim: 582]. He would sometimes ad “wa barakātuh” in the first one [Ṣifat al Ṣalāt (Description of Prayer), p.188].