´It was narrated that Abu Musa said:` “Ali led us in prayer on the day of (the battle of) the Camel, in a way that reminded us of the prayer of the Messenger of Allah (ﷺ). Either we had forgotten it or we had abandoned it. He said the Salam to his right and to his left.”
Brief Explanation
1؎: Battle of Jamal: In Jumada al-Akhirah, 36 AH, this battle took place in Basra between Ali radi Allahu anhu and those demanding retribution for the killers of Uthman radi Allahu anhu.
2؎: According to the Ahl al-Hadith, it is obligatory to exit the prayer by saying the salam. And in another hadith, it is stated that the means of concluding (i.e., finishing and exiting) the prayer is the salam. Now, the correct and well-known view is that one should say salam to the right and to the left. Ibn al-Qayyim said that fifteen companions radi Allahu anhum have narrated two salams; among them are Ibn Mas'ud, Sa'd, Jabir, Abu Musa, Ammar ibn Yasir, Abdullah ibn Umar, Bara', Wa'il, Abu Malik, 'Adi, Taliq, Aws, and Abu Rumthah radi Allahu anhum. Some of these narrations are authentic (sahih), some are good (hasan). There are five hadiths opposing this, in which only one salam is mentioned, and there is disagreement regarding their authenticity. In one narration from Ibn Mas'ud radi Allahu anhu, the word «وبرکاتہ» is added, which Abu Dawud has transmitted from the narration of Wa'il ibn Hujr. And the statement of Imam Malik rahimahullah is that giving only one salam is sufficient. Various narrations regarding salam have been established; therefore, all forms are correct, and acting upon all the established ahadith is legislated and recommended (masnun). However, it is preferable to do more of that manner which the Messenger of Allah sallallahu alayhi wa sallam and his companions practiced more frequently. Also, for these manners, (see: Sifat Salat al-Nabi sallallahu alayhi wa sallam by al-Albani, pp. 187, 188).