The Torah tells us: 

לֹא־יָבֹא עַמּוֹנִי וּמוֹאָבִי בִּקְהַל ה׳… עַל־דְּבַר אֲשֶׁר
לֹא־קִדְּמוּ אֶתְכֶם בַּלֶּחֶם וּבַמַּיִם בַּדֶּרֶךְ בְּצֵאתְכֶם מִמִּצְרָיִם וַאֲשֶׁר
שָׂכַר עָלֶיךָ אֶת־בִּלְעָם בֶּן־בְּעוֹר… (דברים כ״ג:ד–ה). 

  “An Ammonite or Moabite shall not enter into the congregation of Hashem… because they did not greet you with bread and water on the way when you left Egypt, and because they hired Bil‘am son of Be‘or to curse you.” 

  Now wait. Let’s be honest. Which crime sounds worse? Moav
hired Bil‘am to curse, to destroy, to annihilate. Amon? They just didn’t bring
out some bread and water. At worst, a breach of etiquette. 

 So why does the Torah treat them equally? Why are they both forever excluded from joining Am Yisrael?