It wasnarrated that Aswad said:
" 'Abdullah (bin Mas'ud) said: 'Noneof you should apportion within himself a part (of his prayer)thinkingthat it is a right of Allah upon him that he must only turnto hisright to leave after finishing the prayer. I saw the MessengerofAllah (ﷺ) and most of the time he turned to his left.'" (RU)
English reference (RU): Vol. 1, Book 5, Hadith 930 (RU)
Arabic reference (RU): Book 5, Hadith 983 (RU)