Parashas Eikev · Passuk 9:17
Thereupon I gripped the two tablets and flung them away with both my hands, smashing them before your eyes.
Torah Temimah points to Yerushalmi Taanis 4:5.
TT lemma: ואתפש בשני הלחת (unit 2 of 3).
Sefaria — Yerushalmi Taanis 4:5
English: R’ Yochanan said in the name of R’ Yose bar Abaye: The tablets were seeking to fly away, and Moshe held them fast, as it is written, “I seized the two tablets.”
Custom (Yerushalmi — tablets sought to fly)
Moshe’s grip kept the tablets from ascending or fleeing at the moment of the sin.