صحيح مسلم 1309

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

Rapporté par Ibn ‘Umar رضي الله عنه : Lorsque le Messager d’Allah ﷺ s’asseyait pour le tashahhud, il posait sa main gauche sur son genou gauche, sa main droite sur son genou droit, il levait son index (celui à côté du pouce) en faisant des invocations de cette façon, et il étendait sa main gauche sur son genou gauche