When the Messenger of Allah ﷺ sat to say the tashahhud, he placed his left hand on his left thigh and pointed with his forefinger, and his gaze did not go beyond he finger with which he was pointing. (Using translation from Nasāʾī 1275)  

أَنَّ رَسُولَ اللهِ ﷺ «كَانَ إِذَا قَعَدَ فِي التَّشَهُّدِ وَضْعَ كَفَّهُ الْيُسْرَى عَلَى فَخِذِهِ الْيُسْرَى وَأَشَارَ بِالسَّبَّابَةِ لَا يُجَاوِزُ بَصَرُهُ إِشَارَتَهُ»