Sforno on Deuteronomy 23:5/ספורנו על דברים כ״ג:ה׳

1אשר לא קדמו, neither of these two nations met the Israelites, but the Moabites at least gave them bread and water in return for money, as we read in Deut. 2, 28-29 כאשר עשו לי בני עשו היושבים בשעיר והמואבים היושבים בער, “as the Children of Esau who dwell in Seir did for me, as well as the Moabites who dwell in Or.” The Ammonites did not even sell us bread and water. However, the Moabites added to their sin of hostility by hiring the prophet Bileam to curse us. Therefore, לא תדרוש שלומם, for while neither of them have shown basic human civilities, the Moabites have even displayed open hostility.