(a) Qabisah bin Hulb narrates from his father (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) would sometimes turn away from the prayer to his right and sometimes to his left, and he would place one of his hands on the other.
(b) Imam al-Shafi'i (may Allah have mercy on him) said: If the one praying has no need in a particular direction and may turn whichever way he wishes, I prefer that he turn to his right, because the Prophet (peace and blessings be upon him) loved to favour the right; yet he is not put under any constraint in any of that.
(c) Imam al-Bayhaqi (may Allah have mercy on him) said: The report of Sayyidah Aishah (may Allah be pleased with her) has already passed, that the Prophet (peace and blessings be upon him) loved to favour the right in all his affairs.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3613