(21) باب صِفَةِ الْجُلُوسِ فِي الصَّلاَةِ وَكَيْفِيَّةِ وَضْعِ الْيَدَيْنِ عَلَى الْفَخِذَيْنِ
Another version on the authority of Ibn Umar says:
When the Messenger of Allah (ﷺ) sat for tashahhud, he placed his left hand on his left knee and placed his right hand on his right knee, and he formed a ring like (fifty-three) and pointed with his finger of attestation.
Reference: Sahih Muslim 580 b
In-book reference: Book 5, Hadith 148
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 1203