Sahih Muslim
The Book of Prayers (Kitab Al-Salat)
Book Number: 004 / Hadith Number: 1949
'Abdullah b. Zaid al-Ansari reported that the Messenger of Allah (may peace be upon him) went out to the place of prayer in order to offer prayer for rainfall. And when he intended to make supplication he faced Qibla and turned round his mantle.