Musnad Ahmad 793:1

Hashim and Bahz narrated to us, they said: Sulayman ibn al-Mughirah narrated to us, from Humayd ibn Hilal, he said: One who heard the Bedouin narrated to me, he said: "I saw the Messenger of Allah, may Allah bless him and grant him peace, praying." He said: "So he raised his head from the bowing (ruku'), and he raised his palms until they were level with, or reached, the lobes of his ears, as if they were two fans."