Musnad Ahmad 329:31

Sakan ibn Nafi’ narrated to us, he said: Salih ibn Abi al-Akhdar narrated to us, from al-Zuhri, from ‘Abbad ibn Tamim al-Ansari, that he heard his paternal uncle—and he was one of the companions of the Messenger of Allah, may Allah bless him and grant him peace—saying: "The Messenger of Allah, may Allah bless him and grant him peace, went out and sought rain. Then he turned toward the Qibla, and he turned his back to the people while supplicating, and he turned his cloak inside out, and he prayed two rak'ahs." Abu ‘Abd al-Rahman said: He turned the cloak inside out so that the year would change, and the high prices would become cheap.