"Ibn Umar saw me playing with the pebbles while praying. When he finished (praying), he told me not to do that and said: 'Do what the Messenger of Allah ﷺ used to do.' I said: 'What did he used to do?' He said: 'When he sat during the prayer, he placed his right hand on his thigh and clenched all his fingers, and pointed with the finger that is next to the thumb, and he put his left hand on his left thigh."  

وَقَالَ اصْنَعْ كَمَا كَانَ رَسُولُ اللَّهِ ﷺ يَصْنَعُ قُلْتُ وَكَيْفَ كَانَ يَصْنَعُ قَالَ كَانَ إِذَا جَلَسَ فِي الصَّلاَةِ وَضَعَ كَفَّهُ الْيُمْنَى عَلَى فَخِذِهِ وَقَبَضَ يَعْنِي أَصَابِعَهُ كُلَّهَا وَأَشَارَ بِأُصْبُعِهِ الَّتِي تَلِي الإِبْهَامَ وَوَضَعَ كَفَّهُ الْيُسْرَى عَلَى فَخِذِهِ الْيُسْرَى