Albert Barnes Commentary Deuteronomy 23:6

"Thou shalt not seek their peace nor their prosperity all thy days for ever." — Deuteronomy 23:6 (ASV)

That is, “you shall not invite them to be on terms of friendship with you (compare Deuteronomy 20:10 and following), nor make their welfare your care”: compare Ezra 9:12. There is no injunction to hatred or retaliation (compare Deuteronomy 2:9, Deuteronomy 2:19); but later history contains frequent record of hostility between Israel and these nations.