Parashas Ki Sisa · Passuk 34:28
Torah Temimah points to classical source on this unit (verified).
English: “Forty days” — atonement and the second tablets.
Derash on the second forty days without food or water, and the writing of the Ten Words.
He was there with Hashem forty days and forty nights; he ate no bread and drank no water; and he wrote upon the tablets the words of the covenant, the Ten Words.