Moses
Deuteronomy 29:21ESV·traditional attribution

And the LORD will single him out from all the tribes of Israel for calamity, in accordance with all the curses of the covenant written in this Book of the Law.

Matthew Henry Presbyterian @wholebiblehenry

It appears by the length of the sentences here, and by the copiousness and pungency of the expressions, that Moses, now that he was drawing near to the close of his discourse, was very warm and zealous, and very desirous to impress what he said upon the minds of this unthinking people.

Commenting on Deuteronomy 29:10-29

John Gill Reformed Baptist @doctorgill

So that the generation to come of your children that shall rise up after you,.... Not the next generation, but in future times, in ages to come, at a great distance, even after the destruction of Judea by the Romans; to which Deu 29:23 seems to refer: and the stranger that shall come from a far land; on trade and business, or for the sake...

Keil & Delitzsch Lutheran @keilanddelitzsch

Deu 29:20-21 “For the Lord will not forgive him (who thinks or speaks in this way); but then will His anger smoke (break forth in fire; vid., (Psa 74:1), and His jealousy against that man, and the whole curse of the law will lie upon him, that his name may be blotted out under heaven (vid., Deu 25:19; Exo 17:14).

Commenting on Deuteronomy 29:20-21