By indicating, “when you go out,” [“Ki Tetze“] b.Sotah 35b indicates the Torah is automatically excluding the seven nations inhabiting the land… the seven nations that are to be obliterated as the Jews take over the Promised Land. In that way, no Israelite is permitted to marry into one of these seven nations, even if she is captured in war because “when you go out,” indicates leaving the Land of Promise.
In b.Kiddushin 21b, the Rabbis are discussing whether a Cohen is permitted to undergo Retziah [the procedure where one chooses to become a permanent slave to his master… at least until the Yovel or Jubilee]. The reason this is important is retziah ends with an awl boring a hole in the cartilage of the ear, which could effectively render the Cohen a baal mum or defective. The argument arises because Rebbi expounds the retziah passage using the generalizations and specifications method while R’ Yose uses a method of amplification and limitation. This created a great conversation because with A&L, the restrictive clause is understood to be an explanation of the first general clause and limits the cases governed by the clause. In the G&S method [Kelal Uferet], the restrictive clause is seen as an example of the broader clause preceding it.
The Talmud conversation passes into a discussion whether that Cohen can marry a convert or if he must choose a native born [Ezrach]. By digressing into our Torah passage for this week, the Rabbis try to make a point that if an Israelite can marry a captured woman who converts to Judaism, the Cohen should be able to marry a convert. However, the end result is that a Cohen cannot marry a convert because Scripture adds for them more commandments, and the woman captured is not marital material if she does not convert of her own free will as b.Yevamot 48a makes perfectly clear [she must choose to perform the second mikveh of her own free will]. One interesting thing is that the use of the word Isha [woman] in our portion generally denotes a married woman. Since the verse employs this term, it is understood that the Torah’s allowance extends even to a captured woman who was married prior to her conversion. Though not expressly said, I think this is allowed because the assumption is made that her husband died in the battle.
For those who want to know whether the Torah passage for this week indicates the woman is to grow her nails or to pare them, I refer you to b.Yevamot 48a-b. R’ Eliezar and Rabbi Akiva have a lively conversation about that same subject. The only thing I will tell you is that I love it when the Talmudic discussions end with the phrase, “This is indeed a difficulty.”