Sahih Bukhari Volume 2, Book 17, Hadith Number 139

Narated By Abbas bin Tamim : From his uncle who said, “The Prophet went out to the Musalla to offer the Istisqa’ prayer, faced the Qibla and offered a two-Rakat prayer and turned his cloak inside out.” Narrated Abu Bakr, “The Prophet put the right side of his cloak on his left side.”