Rashi on Ki Sisa 32:19

English: וישלך מידו AND HE CAST [THE TABLETS] OUT OF HIS HAND — He said: “What is the law regarding the Paschal lamb which is only one of the commandments? The Torah states: (Exodus 12:43) “No stranger shall eat thereof”! (cf. Rashi on that verse: a stranger means one who has enstranged himself by his doings from his Father in heaven — an apostate). “But the whole Torah is here (written on the tablets) and all the Israelites are apostates, can I possibly give it (the Torah) to them?!” (Shabbos 87a). תחת ההר BENEATH THE MOUNTAIN — i. e. at the foot of the mountain.