Sunan Ibn Majah Book 5, Hadith 110
“I saw the Prophet (ﷺ)
making a circle with his thumb and middle finger, and raising the one
next to it (the index finger), supplicating with it during the
Tashah-hud.”
“I saw the Prophet (ﷺ) putting his right hand on his right thigh during prayer, and pointing with his finger.”
It was narrated from Ibn ‘Umar that the Prophet (ﷺ) used to sit during prayer, putting his hands on his knees and raising his right finger which was next to his thumb, supplicating with it, and with his left hand (spread out) on his knee.