Abbad bin Tamim narrates from his uncle (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) went out to the prayer ground; he (peace and blessings be upon him) prayed for rain, faced the qiblah, turned his cloak inside out and prayed two rak'ahs.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب صلاة الاستسقاء / 6384