וַיִּשְׂאוּ לָהֶם נָשִׂים מֹאֲבִיּוֹת (רות א, ד), תָּנֵי בְּשֵׁם רַבִּי מֵאִיר לֹא גִּיְּרוּם וְלֹא הִטְבִּילוּ אוֹתָם וְלֹא הָיְתָה הֲלָכָה לְהִתְחַדֵּשׁ, וְלֹא הָיוּ נֶעֱנָשִׁין עֲלֵיהֶם, עַמּוֹנִי וְלֹא עַמּוֹנִית, מוֹאָבִי וְלֹא מוֹאָבִית.... רַבִּי בֵּיבַי בְּשֵׁם רַבִּי רְאוּבֵן אָמַר, רוּת וְעָרְפָּה בְּנוֹתָיו שֶׁל עֶגְלוֹן הָיוּ, שֶׁנֶּאֱמַר (שופטים ג, יט): דְּבַר סֵתֶר לִי אֵלֶיךָ הַמֶּלֶךְ וַיֹּאמֶר הָס וגו', וּכְתִיב (שופטים ג, כ): וְאֵהוּד בָּא אֵלָיו וגו' וַיֹּאמֶר אֵהוּד דְּבַר אֱלֹהִים לִי אֵלֶיךָ וַיָּקָם מֵעַל הַכִּסֵּא, אָמַר לוֹ הַקָּדוֹשׁ בָּרוּךְ הוּא אַתָּה עָמַדְתָּ מִכִּסְאֲךָ לִכְבוֹדִי, חַיֶּיךָ הֲרֵינִי מַעֲמִיד מִמְךָ בֵּן יוֹשֵׁב עַל כִּסֵּא ה'. וַיֵּשְׁבוּ שָׁם כְּעֶשֶׂר שָׁנִים, כִּשְׁלשִׁים כְּאַרְבָּעִים אוֹ חָסֵר אוֹ יוֹתֵר.
וַתֹּאמֶר רוּת אַל תִּפְגְּעִי בִי לְעָזְבֵךְ לָשׁוּב מֵאַחֲרָיִךְ (רות א, טז), מַהוּ אַל תִּפְגְּעִי בִי, אָמְרָה לָהּ לֹא תֶחֱטָא עָלַי, לָא תִסְּבִין פְּגָעַיִךְ מִנִּי, לְעָזְבֵךְ לָשׁוּב מֵאַחֲרָיִךְ, מִכָּל מָקוֹם דַּעְתִּי לְהִתְגַּיֵּר, אֶלָּא מוּטָב עַל יָדֵךְ וְלֹא עַל יְדֵי אַחֶרֶת. כֵּיוָן שֶׁשָּׁמְעָה נָעֳמִי כָּךְ הִתְחִילָה סוֹדֶרֶת לָהּ הִלְכוֹת גֵּרִים.
And Ruth said: do not entreat me to leave you, or to return from following you. What does "entreat" [literally "plague" or "hurt"] mean? Ruth said to Naomi, "Do not sin against me; do not turn your plagues away from me. To return from following you. I intend to convert no matter what, but it would be better [to be converted] by your hands than by the hands of another." When Naomi heard this, she immediately began explaining the laws of conversion to her.....
וַתֵּרֶא כִּי מִתְאַמֶּצֶת הִיא לָלֶכֶת אִתָּה (רות א, יח), אָמַר רַבִּי יְהוּדָה בְּרַבִּי סִימוֹן בּוֹא וּרְאֵה כַּמָּה חֲבִיבִים הַגֵּרִים לִפְנֵי הַמָּקוֹם, כֵּיוָן שֶׁנָּתְנָה דַעְתָּהּ לְהִתְגַּיֵּר הִשְׁוָהּ הַכָּתוּב לְנָעֳמִי.
And when she saw that she was determined to accompany her. R. Yehuda the son of R. Shimon said: Come and see how precious converts are before the All-Present One! Once Ruth decided to convert, the Tanakh refers to her equally with Naomi.
Quomodo enim Ruth, cum esset alienigena, Iudaeo nupsit? et qua ratione in Christi generatione eius putauit euangelista copulae conmemorationem esse faciendam, quae legis serie uetabatur? non ergo ex legitima saluator generatione manauit? uidetur esse deforme, nisi ad apostolicam sententiam reuertaris quia lex non est uistis postia, sed iniustis. haec enim cum sit alienigena et Moabitis, praesertim cum lex Moysi prohiberet has nuptias Moabitasque excluderit ab ecclesia..... Quomodo intruvit in ecclesiam nisi quia sancta et inmaculata moribus supra legem facta est? Si enim lex impiis et peccatoribus posita est, utique Ruth, quae definitionem legis excessit et intrauit in ecclesiam et facta est Israhelitis et meruit inter maiores dominici generis conputari, propter cognitionem mentis electa, non corporis, magnum nobis exemplum est quia in illa nostrum omnium, qui collecti ex gentibus sumus ingrediendi in ecclesiam domini, figura praecessit. Hanc igitur aemulemur, ut quia haec moribus hanc praerogatiuam meruit adsciscendae societatis suae, sicut historia docet, nos quoque propter morum electionem in ecclesiam domini meritis suffragantibus adlegamur.
Ambrose of Milan (c. 340-397), Exposition on the Gospel of Luke 3
For how did Ruth, when she was a foreigner, marry a Jew? And for what reason did the Evangelist (Matt. 1:5) believe that this marriage, which was forbidden by the weight of the law, should be included in the genealogy of Christ? Did the Savior therefore descend from an illegitimate heritage? Unless you return to the apostolic principle that the law was not given for the just but for the unjust, then, his genealogy would seem to be deformed, given that Ruth was a foreigner and a Moabite, whereas the law of Moses prohibits marriage to Moabites and excludes them from the church.... Hence, how did she enter the church unless because she was made holy and immaculate by deeds that go beyond the law? For if the law was given for the irreverent and sinners, then surely Ruth, who exceeded the limits of the law and entered the church and was made an Israelite and deserved to be counted among the honored figures of the Lord's genealogy, chosen for kinship of mind, not of body, is a great example for us, because she prefigures all of us who were gathered from the nations for the purpose of joining the church of the Lord. We should emulate her, therefore, who merited by her deeds this privilege of being admitted to his society, as history teaches, so that we also, by our deeds and accompanying merits, might be chosen for election to the church of the Lord.
Lines 46-51 & 260-4 (ed. & trans. Greti Dinkova-Bruun)
Constantique uidens animo Ruth pergere secum,
Non reditum suadere aduersarique uolenti
Vlterius uoluit Noemi, sed mentis eodem
Ac fideo feruore fidem mirata recepit.
Pergentes simul ergo due, uelut una duabus
Mens erat.....
Hec de Ruth tibi scripta puta progressus ab imo
Quisquis es, ad summi culmen perductus honoris
Auctoremque agnosce tuum; sapiensque bonusque
Non quid sis, sed quid fueris meminisse studeto.
Leontius of Paris, Histories of the Old Testament (c. 1180-1200)
Seeing that Ruth would continue steadfastly with her / Naomi did not wish any longer to urge her return and no longer opposed her wishes, but, amazed at her loyalty, / received her with the same ardor of mind and faithfulness. / Then the two proceeded, a pair possessed of a single mind, as it were....
Consider that this tale about Ruth has been written for you, whoever you are, / progressing from the lowest parts and brought to the peak of highest honor, / and recognize your maker. Being both wise and good, / strive to remember not what you are, but what you have been.