Miszna do Izajasza 10:13

On that day Judah, an Ammonite convert, came and stood before them in the house of study. He said to them: Do I have the right to enter into the assembly? Rabban Gamaliel said to him: you are forbidden. Rabbi Joshua said to him: you are permitted. Rabban Gamaliel said to him: the verse says, "An Ammonite or a Moabite shall not enter into the assembly of the Lord: even to the tenth generation" (Deuteronomy 23:4). R. Joshua said to him: But are the Ammonites and Moabites still in their own territory? Sanheriv, the king of Assyria, has long since come up and mingled all the nations, as it is said: "In that I have removed the bounds of the peoples, and have robbed their treasures, and have brought down as one mighty the inhabitants" (Isaiah 10:1. Rabban Gamaliel said to him: the verse says, "But afterward I will bring back the captivity of the children of Ammon," (Jeremiah 49:6) they have already returned. Rabbi Joshua said to him: [another] verse says, "I will return the captivity of my people Israel and Judah" (Jeremiah 30:3). Yet they have not yet returned. So they permitted him to enter the assembly.