Midras Yeremia 48:30: Ruth Rabbah & Bereshit Rabbah

“She descended to the threshing floor, and did in accordance with everything that her mother-in-law instructed her” (Ruth 3:6).
“She descended to the threshing floor.” Regarding Moav it is written: “I know his arrogance [evrato], said the Lord, that it is unfounded; his boasts [badav] [have accomplished nothing well-founded]” (Jeremiah 48:30). Rabbi Ḥanina bar Pappa, Rabbi Simon, and the Rabbis – Rabbi Ḥanina said: The conception [iburo] of Moav was not undertaken for the sake of Heaven, but rather for the sake of licentiousness, as it is stated: “Israel was dwelling in Shittim, [and the people began to engage in licentiousness with the daughters of Moav]” (Numbers 25:1). “Did not his descendants do so”²⁰⁶The midrash interprets the word badav to mean descendants. Combined with a more literal translation of the entire phrase, “his boasts have accomplished nothing well-founded” can be alternately translated “did not his descendants do so.” for the sake of licentiousness and not for the sake of Heaven? “His descendants did so” is not stated, but rather, “they did not do so,” – [they did not act] for the sake of Heaven but for the sake of licentiousness. “Israel was dwelling in Shittim, and the people began to engage in licentiousness.” The Rabbis say: The conception of Moav was undertaken for the sake of licentiousness, but ultimately it was for the sake of Heaven, as it is stated: “She descended to the threshing floor, and did [in accordance with everything that her mother-in-law instructed her].”

“Lot’s two daughters conceived from their father” (Genesis 19:36).
“Lot’s two daughters conceived from their father” – Rabbi Elazar said: A woman never conceives from her initial act of intercourse. But is it not written: “Lot’s two daughters conceived from their father”? (Genesis 19:36). Rabbi Tanḥuma said: They manipulated themselves, broke their hymen, and conceived as though it were from a second act of intercourse.
Rav Naḥman bar Ḥanin said: Anyone who has a ravenous appetite for sexual relations will ultimately be fed his own flesh.²³A metaphor for incest. Rabbi Yudan of Gaul and Rabbi Shmuel bar Naḥman, both in the name of Rabbi Elyehoeini: We do not know whether Lot lusted after his daughters or his daughters lusted after him. From what is written: “The isolated one²⁴Lot, who was isolated from Abraham. seeks lust” (Proverbs 18:1), we see that Lot lusted after his daughters, but his daughters did not lust after him.
Rabbi Tanḥuma bar Rabbi Ḥiyya in the name of Rabbi Hoshaya the interpreter: There is no Shabbat on which one does not read the passage about Lot.²⁵In those days there was apparently a practice to recite the passage about Lot every Shabbat, to warn people not to overindulge in wine. What is the source for this? “The isolated one seeks lust, with all tushiya²⁶Tushiya is a reference to Torah (see Sanhedrin 26a). he will be exposed”²⁷The shame of Lot is exposed for all to reflect upon. (Proverbs 18:1). Rabbi Aḥa said: “They will be exposed” is not written here, but rather, “he will be exposed” – the men [of Amon and Moav] were distanced, but the women were drawn near.²⁸The shame of Lot is preserved for all time, in that the Torah prohibits Moavite and Amonite men from marrying Israelite women (Deuteronomy 23:4). The shame of Lot’s daughters is not preserved, however, because Moavite and Amonite women may marry Israelite men.

That is what is written [concerning Moav]: “I know its fury, the utterance of the Lord, and its lies [badav] are unfounded [lo khen]” (Jeremiah 48:30). Rabbi Huna bar Pappa and Rabbi Simon, Rabbi Huna said: At the beginning of Moav’s conception, it was not for the sake of licentiousness, but rather, for the sake of Heaven.²⁹Lot’s daughters acted out of noble motives, as they thought there was no other way to repopulate the world (see section 8). Thus it is stated: His offshoots [badav] are not like that [lo khen]. They [Moav’s descendants] did not act for the sake of Heaven, but for the sake of licentiousness, as it is stated: “Israel was residing in Shitim, and the people began to engage in licentiousness [with the daughters of Moav]” (Numbers 25:1).³⁰Those Moavites, unlike their forebear, Lot’s daughter, acted out of immoral motivations.
Rabbi Simon said: From the beginning of Moav’s conception it was not for the sake of Heaven, but rather, for the sake of licentiousness, as it is stated: “Its fury [evrato]³¹The Midrash interprets evrato to be related to ibur, conception.…its lies [badav] are unfounded [lo khen]”– his offshoots [badav]³²Badav can mean either lies or offshoots. did not act this way [lo khen] – [they did not act] for the sake of licentiousness, but for the sake of Heaven, as it is stated: “She³³Ruth the Moavite. went down to the threshing floor, and acted in accordance with everything that her mother-in-law had commanded her” (Ruth 3:6).³⁴By lying down next to Boaz as he slept.
Rabbi Levi said: If Moav’s beginning was for the sake of licentiousness, his later act was also for the sake of licentiousness, [and the verse is to be interpreted:] Did his offshoots [badav] not do so as well [lo khen]? “Israel was residing in Shitim…” And if the beginning of his conception was for the sake of Heaven, his end was also for the sake of Heaven, [and the verse is to be interpreted:] Did his offshoots [badav] not do so as well [lo khen]? “She went down to the threshing floor.”