When the Messenger of Allah ﷺ sat during the prayer, he put his hands on his knees and raised the finger that is next to the thumb, and supplicates with it, and his left hand was on his knee laid on it. (Using translation from Nasāʾī 1269)
أَنَّ رَسُولَ اللهِ ﷺ كَانَ إِذَا جَلَسَ فِي الصَّلَاةِ وَضَعَ يَدَيْهِ عَلَى رُكْبَتَيْهِ وَرَفَعَ أُصْبُعَهُ الْيُمْنَى الَّتِي تَلِي الْإِبْهَامَ فَدَعَا بِهَا وَيَدُهُ الْيُسْرَى عَلَى رُكْبَتِهِ بَاسِطَهَا عَلَيْهَا