Qatadah narrates from al-Hasan that the Companions of the Messenger of Allah (peace and blessings be upon him) (may Allah be pleased with them) used to raise their hands when they bowed, and also when they raised their heads from the bowing; it looked as though their hands were like fans.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2524