John Calvin Commentary Deuteronomy 28:37

"And thou shalt become an astonishment, a proverb, and a byword, among all the peoples whither Jehovah shall lead thee away." — Deuteronomy 28:37 (ASV)

And you shall become an astonishment. The climax of their miseries is here added: that they should be so far from receiving consolation from men, that on every side their misery should meet with taunts and insults. For nothing more bitterly wounds the wretched than this indignity of being harassed by reproaches and sarcasms. And thus, to be a laughing-stock and byword to all nations is a dreadful infliction.

Again, there is an implied antithesis between the ignominy to which God condemns His ungrateful people and the extraordinary dignity with which He had honored them, so that they should be illustrious before the whole world.

Hence, the Prophets have often imitated this mode of expression; I will not quote the instances of it which occur everywhere.