Genesis 19:36

After these things, therefore, Lot ascends into the mountains, and there "he dwells in a cave," as the Scripture says, "he and his two daughters." The law also should be thought to have ascended, because an embellishment was added to it by the temple built by Solomon, when it became indeed "the house of God, a house of prayer." Evil inhabitants, however, made it "a den of thieves." Therefore "Lot and his two daughters dwelt in a cave." The prophet evidently describes these two daughters saying that Oholah and Oholibah are two sisters, and Oholah indeed is "Judah" and Oholibah is "Samaria." The people therefore divided into two parts made the two daughters of the law. Those daughters, desiring carnal offspring to be preserved and the forces of earthly dominion to be fortified by an abundant posterity, depriving their father of sense and making him sleep, that is, covering and obscuring his spiritual understanding, draw only carnal understanding from him. Then they conceive. Then they give birth to such sons as their father neither perceives nor recognizes. For it was neither the understanding nor the will of the law to beget carnally. But the law is deprived of its sense that such posterity might be begotten that "shall not enter the assembly of the Lord." "For the Ammonites," Scripture says, "and Moabites shall not enter the assembly of the Lord unto the third and fourth generation and forever."

As we have been able, we have carved out these explanations according to the spiritual understanding of Lot and his wife and daughters. We pass no judgment on those who have been able to perceive something more sacred from this text.But above, in the moral sense, we referred Lot indeed to the rational understanding and the courageous soul; but his wife, who looked back, we said to be the flesh given to concupiscence and pleasures. Do not, O hearer, receive these things carelessly. For you ought to watch lest perhaps even when you have fled the flames of the world and have escaped the fires of the flesh, even when you have risen above "Zoar, the city" that is "small and not small," which is somewhere in the middle … you seem to have ascended to the height of knowledge, as to some mountain peak. Beware lest those two daughters lie in wait for you, who do not depart from you but follow you even when you ascend the mountain. They are vainglory and her older sister, pride. Beware lest with their embraces those daughters constrict you, deprived of sense and sleeping, while you seem neither to perceive nor know. They are called daughters because they do not come upon us from outside but proceed from us and from a kind of innocence, as it were, of our acts. Be vigilant, therefore, as much as you can, and watch lest you beget sons from these daughters, because those who have been born from them "shall not enter the assembly of the Lord." But if you wish to beget, beget in the spirit, since "he who sows in the spirit, of the spirit shall reap life everlasting." If you wish to embrace, embrace wisdom and "say wisdom is your sister," that Wisdom also may say of you: He "who shall do the will of my Father who is in heaven, he is my brother and sister and mother." Jesus Christ our Lord is this wisdom, "to whom be glory and sovereignty forever and ever. Amen."

(Versed. 36 seqq.) And the two daughters of Lot conceived by their father, and the firstborn son was born and she called his name Moab. He is the father of the Moabites to this day. And the younger, she also gave birth to a son, and she called his name Ammon, that is, son of my people. He is the father of the Ammonites. The name Moab means 'from the father' and has its etymology in it. But Ammon, whose name is given as if a cause, is derived as son of my race, or as it is better in Hebrew (), son of my people, so it is derived partly from the meaning of the name, partly from the language itself: Ammi, from whom the Ammonites are called, means my people.

Thus were both the daughters of Lot with child by their father.