His father told him that he saw the Messenger of Allah ﷺ sitting when praying, putting his right forearm on his right thigh and raising his forefinger, which he had bent slightly, and he was supplicating. (Using translation from Nasāʾī 1274)   

رَأَيْتُ رَسُولَ اللهِ ﷺ وَهُوَ قَاعِدٌ فِي الصَّلَاةِ قَدْ وَضَعَ ذِرَاعَهُ الْيُمْنَى عَلَى فَخِذِهِ الْيُمْنَى رَافِعًا بِأُصْبُعِهِ السَّبَّابَةِ قَدْ حَنَاهَا شَيْئًا وَهُوَ يَدْعُو  

"I saw the Messenger of Allah ﷺ putting his right hand on his right thigh when praying and pointing with his finger." (Using translation from Nasāʾī 1271)  

رَأَيْتُ رَسُولَ اللهِ ﷺ وَاضِعًا يَدَهُ الْيُمْنَى عَلَى فَخِذِهِ الْيُمْنَى فِي الصَّلَاةِ يُشِيرُ بِأُصْبُعِهِ