Musnad Abu Ya'la al-Mawsili 154:137

Muhammad ibn 'Abbad narrated to us, Sufyan narrated to us, Yahya ibn Sa'id narrated to us from him, and I asked him—meaning Muslim—and Muslim ibn Abi Maryam narrated to me that he heard 'Ali ibn 'Abd al-Rahman al-Ansari. And he also said: 'Ali ibn 'Abd al-Rahman al-Mu'awi narrated to me, saying: I prayed beside Ibn 'Umar, and I began to turn the pebbles. He said: "Do not turn the pebbles, for the turning of pebbles is from Satan. Do as you saw the Messenger of Allah, may Allah bless him and grant him peace, do." I said: "O Abu 'Abd al-Rahman, how did you see him do?" He said: "Like this," and he placed his left hand on his left thigh and his right hand on his right thigh, and he gestured with the one next to the thumb. Muslim said: It reached us that it is a repeller of Satan, and that a person should not testify while he is doing with his hand like this.