Ibn 'Umar reported that when the Messenger of Allah (ﷺ) sat for tashahhud he placed his left hand on his left knee. and his right hand on his right knee. and he raised his right finger, which is next to the thumb, making supplication in this way, and he stretched his left hand on his left knee.
وَحَدَّثَنِي مُحَمَّدُ بْنُ رَافِعٍ، وَعَبْدُ بْنُ حُمَيْدٍ، قَالَ عَبْدٌ أَخْبَرَنَا وَقَالَ ابْنُ رَافِعٍ، حَدَّثَنَا عَبْدُ الرَّزَّاقِ، أَخْبَرَنَا مَعْمَرٌ، عَنْ عُبَيْدِ اللَّهِ بْنِ عُمَرَ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، أَنَّ النَّبِيَّ صلى الله عليه وسلم كَانَ إِذَا جَلَسَ فِي الصَّلاَةِ وَضَعَ يَدَيْهِ عَلَى رُكْبَتَيْهِ وَرَفَعَ إِصْبَعَهُ الْيُمْنَى الَّتِي تَلِي الإِبْهَامَ فَدَعَا بِهَا وَيَدَهُ الْيُسْرَى عَلَى رُكْبَتِهِ الْيُسْرَى بَاسِطُهَا عَلَيْهَا .
Muslim
The Book of Mosques and Places of Prayer • Hadith 147