(5) "Therefore a man will abandon." It was taught: a convert that converted and was married to his sister, whether from the mother or the father - it is acceptable, according to Rabbi Meir. The Sages say: from the mother it is acceptable, from the father, it must be established that he does not worship idols. A refutation arose: does it not say: "And moreover, she is my sister, the daughter of my father..." (Genesis 20:12)! He said to them: reply to them by their own reasoning. Rabbi Meir refuted: "Therefore a man will abandon his father and his mother" (Genesis 2:24). Rabbi Yochanan said: they explained this verse "therefore a man will abandon his father and his mother" the one who supports his father, the one who supports his mother. Rabbi Abahu refuted: does it not say: "And Amram took Yocheved his cousin" (Exodus 6:20)! Rabbi Shimon the son of Rabbi Abahu said: from here would we learn that at the time of the children of Noah, Israel acted differently, before the giving of the Torah!? Rabbi Levi said: we explain the verse "therefore a man will abandon..." the one who is supported by his father, or by his mother. Rabbi Abahu in the name of Rabbi Yochanan said: the children of Noah, in matters of marriage are obligated, in matters of engagement are not. Rabbi Yonah in the name of Rabbi Shmuel said: if a whore is in the marketplace, and two men come to her, the first is exempt and the second is liable, because he was sleeping with a married woman. Did the first one intend to acquire her [as a wife]?! It is said: intercourse at the time of the children of Noah acquires, even not in the way of [later] Judaism. And how do we know that they did not divorce? Rabbi Yehuda in the name of Rabbi Simon and Rabbi Chanin in the name of Rabbi Yochanan said: they did not divorce, or they both divorced each other. Rabbi Yochanan said: his wife divorced him and gave him a bill of divorce. Rabbi Hiyya taught: an idol-worshipper that divorced his wife, and she went and married someone else, and then they both went and converted to Judaism, I do not apply to them the verse "The first husband that sent her away cannot..." (Deuteronomy 24:4). Rabbi Aha in the name of Rabbi Hanina bar Pappa said: in the whole book of Malachi it is written 'Hashem, Lord of Hosts' but here it is written 'the God of Israel' as it says: "For I hate sending away, said Hashem, God of Israel" (Malachi 2:16) - as if to say, God's name only rests on Israel. Rabbi Haggai said: When Israel was exiled, the women's faces were blackened from the sun, and they were left and the men went and married Amonite women. They went and circled the altar, crying, as Malachi says: "And this do a second time" (Malachi 2:13) - a second time in relation to Shittim. "Cover with tears the altar of Hashem with wailing and sighing" (ibid.), the Holy One Blessed be He said: who will accept these tears and wailing, since you stole and did violence to and took it's beauty from her, now you will send her away? And how do we know that they were fastidious about sexual impropriety like Israel? As it says: "And he cleaved to his wife" (Genesis 2:24) and not the wife of his friend, or another man, or an animal. Rabbi Shmuel and Rabbi Abahu and Rabbi Eleazar in the name of Rabbi Hanina said: a child of Noah who comes to his wife unnaturally is liable for the death penalty. Rabbi Assi said: every crime written about the children of Noah is not judged on the metric of positive and negative commandments; rather, they all require the death penalty. How do we know this? "And he cleaved to his wife and they became as one flesh" (ibid.).