DEUT1214 Offering Accommodations to a Stranger. Derech eretz dictates that upon seeing a stranger enter a city, one should ask him whether he has a place of lodging. As the Talmud (Bava Kama 92a) states, "A stranger who comes to town seeking lodging should be questioned concerning lodging, while one who comes to town accompanied by a woman should not be questioned regarding whether she is his wife or his sister. Avimelech the king of the Philistines failed in this; he did make inquiries regarding Sarah's matrimonial status and eventually brought her to his palace. He was then told by Hashem to return Sarah to her husband--otherwise Avimelech would have died, for he should have learned how to receive a stranger coming to his town, and he did not learn." Rashi explains that the words "he should have learned" refer to derech eretz. This teaches us that offering a stranger lodging is an obligation stemming from the principles of derech eretz, and not just a praiseworthy fulfillment of hachnassas orchim. The male descendants of the nation of a Amon and Moav are not permitted to marry a Jewess as a consequence of their failing to come forth and offer bread and water to the Jewish people when they approach their land [this verse].