Sahih Muslim 1308
The Book of Mosques and Places of Prayer
حَدَّثَنَا قُتَيْبَةُ، حَدَّثَنَا لَيْثٌ، عَنِ ابْنِ عَجْلاَنَ، ح قَالَ وَحَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، - وَاللَّفْظُ لَهُ - قَالَ حَدَّثَنَا أَبُو خَالِدٍ الأَحْمَرُ، عَنِ ابْنِ عَجْلاَنَ، عَنْ عَامِرِ بْنِ عَبْدِ اللَّهِ بْنِ الزُّبَيْرِ، عَنْ أَبِيهِ، قَالَ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم إِذَا قَعَدَ يَدْعُو وَضَعَ يَدَهُ الْيُمْنَى عَلَى فَخِذِهِ الْيُمْنَى وَيَدَهُ الْيُسْرَى عَلَى فَخِذِهِ الْيُسْرَى وَأَشَارَ بِإِصْبَعِهِ السَّبَّابَةِ وَوَضَعَ إِبْهَامَهُ عَلَى إِصْبَعِهِ الْوُسْطَى وَيُلْقِمُ كَفَّهُ الْيُسْرَى رُكْبَتَهُ .
Abdullah b. Zubair narrated on the authority of his father that when the Messenger of Allah (ﷺ) sat for supplication, i. e. tashahhud (blessing and supplication), he placed his right hand on his right thigh and his left hand on his left thigh, and pointed with his forefinger, and placed his thumb on his (milddle) finger, and covered his knee with the palm of his left hand
Text from the public-domain hadith-api dataset. Numbering follows that dataset and can differ by a few from some printed editions — check the wording, not only the number.