مختصر صحيح بخاري
Mukhtasar Sahih Bukhari
Book of Prayer
Placing part of garment on shoulder when praying in one cloth
Narrated Abu Huraira (may Allah be pleased with him): I bear witness that I heard the Messenger of Allah (peace and blessings of Allah be upon him) say: Whoever prays in a single garment should separate its two ends (i.e., place the right end on the left shoulder and the left end on the right shoulder).