Deuteronomy 29:21

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 of travelling, his road either lying through it, or his curiosity leading him to see it:

shall say, when they see the plagues of the land; cities and towns in ruins, fields lie uncultivated, and the whole land depopulated, and all become a barren wilderness, which was once a fruitful country, a land flowing with milk and honey:

and the sicknesses which the Lord hath laid upon it; upon the inhabitants of it, as the pestilence and other diseases, which shall have swept the land of them; see Deu 28:22. This case supposes a general departure from the worship of God to the service of idols; otherwise single individuals are punished in their own persons, as in the Deu 29:21.

John Gill's Exposition of the Whole Bible (1746–1763) — public domain (CC PDM 1.0). Text via the HelloAO Bible API.

Deu 29:21 And the LORD shall separate him unto evil out of all the tribes of Israel, according to all the curses of the covenant that are written in this book of the law:

Ver. 21. And the Lord shall separate him unto evil.] Shall single him out as an object of his wrath; as the huntsman severeth out from the rest a stag to hunt for that day.

John Trapp, A Commentary or Exposition upon All the Books of the Old and New Testament (1647–1656) — public domain. Text from a community e-Sword module.

29:21 Book of Instruction (literally book of the torah): Here, this phrase refers to all of Deuteronomy, of which the list of curses (ch 28) is a part (see 27:3).

Tyndale Open Study Notes — © Tyndale Open Resources, licensed CC BY-SA 4.0. Text via the HelloAO Bible API.

(21, 22) And the Lord shall separate him unto evil . . . so that the generation to come . . . shall say . . . of that land.—It is not a little remarkable that the sin of one man is here represented as growing and spreading devastation over the whole land of Israel—the very thing which the man apparently regards as impossible in his inward reasonings, described in Deu_29:19. Yet is not this the true anticipation of what actually occurred? Comp. 1Ki_14:15-16 : “The Lord shall root up Israel out of this good land, which He gave to their fathers . . . and He shall give Israel up because of the sins of Jeroboam, who did sin, and who made Israel to sin” And what Jeroboam was to Israel, Manasseh was to Judah (Jer_15:4): “I will cause them to be removed into all kingdoms of the earth, because of Manasseh the son of Hezekiah, king of Judah, for that which he did in Jerusalem.”

A Bible Commentary for English Readers, edited by Charles John Ellicott (1878–1897) — public domain. Text from a community e-Sword module.

21. separate] See on Deu_4:41. Unto evil, Jer_21:10; Jer_29:11; Jer_38:4; Jer_39:16; Jer_44:11; Jer_44:27; Jer_44:29; but also in Amo_9:4, Jdg_2:15 (deuteronomic).

this book of the law] See Deu_28:61.

22–28 illustrate the last clause of 19 and predict how the whole land and people shall suffer for the sins of the idolaters.

The Cambridge Bible for Schools and Colleges (gen. ed. J. J. S. Perowne; Cambridge University Press, 1878–1918) — public domain. Text from a community e-Sword module.

Unto evil, i.e. unto some peculiar and exemplary plague; he will make him a monument of his displeasure to the whole land.

According to all the curses of the covenant; he intimates that the covenant of grace, which God made with them, hath not only blessings belonging to it, as this foolish person imagined, but curses also to the transgressors of it.

Matthew Poole's English Annotations on the Holy Bible (1683–1685) — public domain. Text from a community e-Sword/MySword module.

Unto evil - Unto some peculiar and exemplary plague; he will make him a monument of his displeasure to the whole land.

John Wesley, Explanatory Notes Upon the Whole Bible (1754–1765) — public domain. Text via the GEBible commentary corpus.

AND THE REMOTE GENERATION, YOUR CHILDREN THAT SHALL RISE UP AFTER YOU, SHALL SAY. For the tribes of Israel in the first generation already knew [the cause of the disaster] for they heard the imprecations of the covenant [and therefore he states that the future generation will inquire into the cause of the disaster]. It is possible that this verse refers back to the root that beareth gall and wormwood, that when this occurs in future generations, they will inquire into its cause.

Ramban (Nachmanides) on the Tanakh — English translation: “Commentary on the Torah by Ramban (Nachmanides). Translated and annotated by Charles B. Chavel. New York, Shilo Pub. House, 1971-1976” (CC BY 4.0). Text via Sefaria.

The latter generation will say. This refers to both your children, and also the gentiles who see the plagues in your land.

Ibn Ezra on the Tanakh — English translations: “Sefaria Community Translation” (CC0 1.0 (public-domain dedication)); “Yalkut, Sifsei Chachomim Chumash, Metsudah Publications, 2009” (CC BY 4.0); and “Commentary of Ibn Ezra on Isaiah - trans. by M. Friedlander, 1873” (public domain). Text via Sefaria.