The Messenger of Allah ﷺ used to make supplication at Arafah. Hasan added that he would raise his hands like this, placing their backs upward and their palms downward. Hammad demonstrated this, raising his hands with his palms facing the ground.
حدثنا عفان وحسن قالا ثنا حماد عن بشر بن حرب
كان رسول الله ﷺ يدعو بعرفة قال حسن ويرفع يديه هكذا يجعل ظاهرهما فوق وباطنهما أسفل ووصف حماد ورفع حماد يديه وكفيه مما يلي الأرض