Deuteronomy 23:4
3 No Ammonite or Moabite may enter the assembly of the Lord; to the tenth generation none of their descendants shall ever do so, 4 for they did not meet you with food and water on the way as you came from Egypt, and furthermore, they hired Balaam son of Beor of Pethor in Aram Naharaim to curse you. 5 But the Lord your God refused to listen to Balaam and changed the curse to a blessing, for the Lord your God loves you. 6 You must not seek peace and prosperity for them through all the ages to come.
Judith 14:10
5 But before you do all this, bring Achior the Ammonite to me so that he may see and recognize the man who despised the house of Israel and sent him to us as if to his death." 6 So they summoned Achior from the house of Uzziah. When he came and saw the head of Holofernes in the hand of one of the men in the assembly of the people, he fell down on his face in a faint. 7 When they raised him up he threw himself at Judith's feet, and did obeisance to her, and said, "Blessed are you in every tent of Judah! In every nation those who hear your name will be alarmed. 8 Now tell me what you have done during these days." So Judith told him in the presence of the people all that she had done, from the day she left until the moment she began speaking to them. 9 When she had finished, the people raised a great shout and made a joyful noise in their town. 10 When Achior saw all that the God of Israel had done, he believed firmly in God. So he was circumcised, and joined the house of Israel, remaining so to this day.
Notes and References
"... Both Tobit and Tobias are in all respects exemplary Jews living in a Gentile environment, solicitous in prayer (3:1–6; 12:8), almsgiving (1:16–17; 4:7–11), fasting (12:8), dietary regulations (1:10–11), and care for the dead (1:17–20; 2:3–8). Tobit marries a woman from his own clan (1:9) and warns his son against marriage with a woman outside of the extended kinship network (4:12–13), but this admonition is simply in keeping with the immemorial custom of clan-endogamous marriage, not for reasons of ritual purity. Judith is almost ostentatiously scrupulous in such matters as dietary laws (Judith 11:12; 12:1–4, 19), fasting (8:6), ritual washing (12:7–8), and tithing (11:13–15), and she remains a widow after the death of her husband (16:22). The author presents her as the female ideal of piety and strict adherence to the law, yet permits Achior to be circumcised and admitted to the household of Israel in defiance of the Deuteronomic law (Judith 14:10; Deuteronomy 23:4–7). The Moabite woman Ruth is also accepted into the Israelite people notwithstanding the same exclusionary law ..."
Blenkinsopp, Joseph Essays on Judaism in the Pre-Hellenistic Period (p. 211) De Gruyter, 2017