You shall not seek their peace nor their prosperity all your days forever.
Deuteronomy 23:6
Surrounding context
23:5 Nevertheless the LORD your God would not listen to Balaam, but the LORD your God turned the curse into a blessing for you, because the LORD your God loves you.
23:6 You shall not seek their peace nor their prosperity all your days forever.
23:7 "You shall not abhor an Edomite, for he is your brother. You shall not abhor an Egyptian, because you were an alien in his land.