Halakhah su Deuteronomio 21:11

According to the Meshech Chochmah, the permission to eat non-kosher foods is implicitly discouraged by the Torah, not unlike the Torah’s implicit discouragement (see Rashi to Devarim 21:11 s.v. V’lakachta) of engaging the eishet yefat to’ar described in Devarim 21:10-14. He understands the permission as a concession to the yeitzer hara (evil inclination; see Kiddushin 21b) and as something that maximum efforts should be made to avoid. The Rambam’s permission might be compared to the permission to eat on Yom Kippur granted to the one bringing the sa’ir laAzazel (see Vayikra 16:21-22) to the desert cliff. The Mishnah (Yoma 66b-67a) states that food was offered him at each of the ten stations located on the route from the Beit Hamikdash to the cliff. The Gemara (ibid.) notes that no one who walked the sa’ir hamishtalei’ach ever partook of the food on Yom Kippur but the very fact that it was permitted to us helped them because of the paradoxical principle of eino domeh mi sheyeish lo pat b’salo lemi she’ein lo pat b’salo: one who has the option to eat cannot be compared to one who does not have what to eat. When one is given the option to eat he is less desirous of the food than he would have been had it been forbidden to him. Similarly, it is possible that even the Rambam believes that the Torah permits the soldier to eat non-kosher food when behind enemy lines in order to (paradoxically) help him resist the temptation to eat non-kosher food.

That is that He commanded us about the law of the [captive woman of] beautiful form. And that is His, may He be exalted, saying, "And you see among the captives, etc." (Deuteronomy 21:11). And the regulations of this commandment have already been explained in the first chapter of Kiddushin. (See Parashat Ki Tetzei; Mishneh Torah, Kings and Wars)

To execute the law of the one of beautiful form (yefat toar) as is written in the Torah: That we were commanded about the woman of beautiful form to do to her like the statute that is written in this section, as it is stated (Deuteronomy 21:11), "And you shall see among the captives a woman of beautiful form" - meaning to say that she be beautiful in his eyes (see Mishneh Torah, Laws of Kings and Wars 8:3). And the content of the command about her is that the Israelite bring her to his home and command her to shave her head, to grow her nails, to remove from upon her the fine garment that she brought from her home - as such was the custom of the nations, that their daughters would adorn themselves in war for harlotry - and to allow her to cry for her father and mother a month of days, as per her desire. These are the things that are explicit in Scripture about the law of a woman of beautiful form. And it would seem that the obligation of a positive commandment comes on all of these [things].