Narrated Sulaiman bin Harb:
"Hammad bin Salamah narrated to us, from Thabit, from Anas, that the Prophet (ﷺ) recited this Ayah: So when his Lord appeared to the mountain, He made it collapse to dust (7:143) - Hammad said: "Like this." Sulaiman held his thumb over the tip of his finger on the right hand (so that only the tip of one finger was protruding) - and he [the Prophet (ﷺ)] said: "So the mountain fainted. 'And Musa fell down unconscious.'"
English reference: Vol. 5, Book 44, Hadith 3074
Arabic reference: Book 47, Hadith 3353