Midrash for Judges 3:13

“The adversary extended his hand over all her delights; for she saw the nations entering her Sanctuary, whom You had commanded that they should not enter Your assembly” (Lamentations 1:10).
“The adversary extended his hand.” You find that when the enemies entered the Temple, Amonites and Moavites entered with them. Everyone was running to plunder silver and gold, and the Amonites and Moavites were running to plunder the Torah, in order to remove “An Amonite and Moavite shall not enter the assembly of the Lord” (Deuteronomy 23:4). Rabbi Yehuda ben Rabbi Simon [said] in the name of Rabbi Levi ben Perata: This is analogous to a conflagration that was ignited in a king’s palace. Everyone was running to plunder the silver and the gold while a slave ran to plunder his writ of servitude. So too, when the enemies entered the Temple, Amonites and Moavites entered with them. Everyone was running to plunder silver and gold, and the Amonites and Moavites were running to plunder the Torah, in order to remove “An Amonite and Moavite shall not enter the assembly of the Lord.”
Abraham bestowed four good things upon Lot. That is what is written: “Abram went, as the Lord had spoken to him, and Lot went with him” (Genesis 12:4). And it says: “Lot, too, who was going with Abram [had sheep, cattle and tents]” (Genesis 13:5). And it says: “He returned all the property, [and also his brother Lot and his property he returned]” (Genesis 14:16). And it says: “It was when God destroyed the cities of the plain [God remembered Abraham, and He sent Lot from the midst of the upheaval]” (Genesis 19:29). Correspondingly, they should have repaid them with goodness;¹⁴³Lot’s descendants, the nations of Amon and Moav, should have been kind to Abraham’s descendants. however, they performed acts of wickedness. That is what is written: “He sent messengers to Bilam…now, please go and curse for me…. The elders of Moav and the elders of Midian went…” (Numbers 22:5–7). “He gathered to him the children of Amon and Amalek, [and he went and smote Israel]” (Judges 3:13).¹⁴⁴The verse is stated regarding Eglon, king of Moav. “It was thereafter, the children of Moav, and the children of Amon, and with them some Amonites, came against Yehoshafat” (II Chronicles 20:1). And this: “The adversary extended his hand...”
Correspondingly, their sins are written in four places. “An Amonite and Moavite [shall not enter the assembly of the Lord]…because they did not greet you with bread and with water…” (Deuteronomy 23:4–5). “My people, remember now what Balak king of Moav devised…” (Micah 6:5). “Because they did not greet the children of Israel with bread and with water, and hired Bilam against them, to curse them” (Nehemiah 13:2). “He sent and summoned Bilam son of Beor to curse you” (Joshua 24:9).
Correspondingly, four prophets stood and sealed their sentence, and they were: Isaiah, Jeremiah, Ezekiel, and Zephaniah. Isaiah said: “A prophecy of Moav: For on the night that Ar of Moav is plundered, it is ruined; for on the night that Kir of Moav is plundered, it is ruined” (Isaiah 15:1). Jeremiah said: “Behold, days are coming, the utterance of the Lord, and I will sound to Raba of the children of Amon an alarm of war, and it will become a mound of desolation, and its environs will be burned in fire, and Israel will inherit its inheritors, said the Lord” (Jeremiah 49:2). Ezekiel said: “To the children of the east, against the children of Amon, and I will give it as a heritage, so that the children of Amon will not be remembered among the nations. I will administer punishments to Moav, and they will know that I am the Lord” (Ezekiel 25:10–11). Zephaniah said: “Therefore, as I live, the utterance of the Lord of hosts, God of Israel, Moav will be like Sodom and the children of Amon like Gomorrah, a rustling thornbush, a salt mine, a desolate wasteland forever. The remnant of My people will plunder them and the rest of My nation will inherit them” (Zephaniah 2:9).

... R’ Shimon bar Aba said in the name of R’ Yochanan: any where that it says ‘and it was’ (vayehi) it indicates distress and joy. If it is distress there is no distress like it and if it is joy there is no joy like it. R’ Shmuel ben Nachmani came and split the teaching in half. Anywhere that it says ‘and it was’ (vayehi) indicates distress, ‘and it will be’ (v’haya) indicates joy…The brought a challenge from this verse “…and he was [there] (v’haya) when Jerusalem was taken.” (Jeremiah 38:28) He said to them: this is still a cause of joy because on that very day Israel received full payment for their sins. As R’ Shmuel ben Nachmani said: Israel received full payment for their sins on the day the Holy Temple was destroyed, as it says “Your iniquity is finished, O daughter of Zion…” (Lamentations 4:22)