Joseph Benson's Commentary of the Old and New Testaments - Deuteronomy 23:3
Deuteronomy 23:3. An Ammonite or a Moabite The Jews will have it, that the women of these two nations were not concerned in this law. And that though an Israelitish woman might not marry an Ammonite or Moabite, yet a man of Israel might marry one of their women, after she professed the Jewish religion. For ever This seems to denote the perpetuity of this law, that it should be inviolably observed in all succeeding ages. read more
Albert Barnes' Notes on the Whole Bible - Deuteronomy 23:3-5
This law forbids only the naturalization of those against whom it is directed. It does not forbid their dwelling in the land; and seems to refer rather to the nations than to individuals. It was not understood at any rate to interdict marriage with a Moabitess; compare Ruth 1:4; Ruth 4:13. Ruth however, and her sister were doubtless proselytes.Deuteronomy 23:4Compare the marginal reference. The Moabites and the Ammonites are to be regarded as clans of the same stock rather than as two... read more