Sunan Ibn Majah
912
Sahih+2

It was narrated that Wa’il bin Hujr said:“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.”

SahihAl-Albani
SahihMuhammad Fouad Abd al-Baqi