Yahya related to me from Malik from Muslim ibn Abi Maryam thatAIi ibn Abd ar-Rahman al-Muawi said, "Abdullah ibn Umar saw me playingwith some small pebbles in the prayer. When I finished he forbade me,saying, 'Do as the Messenger of Allah, may Allah bless him and granthim peace, did.' I said, 'What did the Messenger of Allah, may Allahbless him and grant him peace, do?' He said, 'When he sat in theprayer, he placed his right hand on his right thigh and he closed hisfist and pointed his index finger, and he placed his left hand on hisleft thigh. That is what he used to do.' "
App reference: Book 3, Hadith 51
USC-MSA web (English) reference: Book 3, Hadith 51
Arabic reference: Book 3, Hadith 198