Abu Ma'mar said: In Mecca, I prayed behind a man and he turned his head to both sides (for salam). I mentioned this to Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him), so he said: From where did he get this (Sunnah)? And Hakam said: The Noble Prophet (peace and blessings be upon him) used to do the same.
Hadith Referenceسنن دارمي / من كتاب الصللاة / 1384
Hadith Takhrijاس روایت کی سند صحیح ہے۔ دیکھئے: [مسلم 581] ، [أبويعلی 5244]
Brief Explanation
(Explanation of Ahadith 1382 to 1384) According to the statement of Hukm, Sayyiduna Ibn Mas'ud radi Allahu anhu was of the opinion of turning the salam (salutation) to one side only, but this is not correct. The noble Companions (Sahabah kiram) used to turn the salam to both sides, and this is the Sunnah and obligatory (wajib) practice.