Halakhah for Sanhedrin 170:18

He prohibited us from exploiting a captive woman (yefat toar) after one has sexual intercourse with her. [This] means to say that he does not work her and leave her to be like one of the other maidservants that serve as slaves. And that is His saying, "you shall not exploit her, since you have afflicted her" (Deuteronomy 21:14). And the language of the Sifrei (Sifrei Devarim 214:5) is, "'You shall not exploit her' - you shall not use her." Behold it has been made clear to you that these two negative commandments are prohibiting two separate matters. And that is that He prohibits from selling her to someone besides him; and also from leaving her with him in the manner of slavery. Rather he should do, like that which He, may He be exalted, commanded - "you shalt let her go where she will." And so did they explain in Sanhedrin (Sanhedrin 85b) about one who kidnaps a soul, from His saying, "and he exploited him and sold him" (Deuteronomy 24:7). They said, "It is from when he brings him into his domain and uses him." And the laws of the captive woman have been explained in the first [chapter] of Kiddushin. (See Parashat Ki Tetzei; Mishneh Torah, Kings and Wars 8.)

Not to make her serve after he has intercourse with her: That we should not make a [captured] 'woman of beautiful form' serve, after intercourse with her. And about this it is stated (Deuteronomy 21:14), "you shall not abuse (titaamer) her, since you afflicted her." The explanation of "abuse" is that is an expression of service. And so did they say in Sifrei, "'You shall not abuse her' - you shall not take service from her." And the matter is that we should not set her up as a concubine or as maid-servant in bondage. And the matter of the verse is not that we should not have her serve any service that women do for their husbands. [Rather] Scripture prohibits making her into a maid-servant, [just] like it is also forbidden to sell her as a maid-servant, and the intention is one. And so too with the stealing of a soul from his brothers (kidnapping), about which it is written (Deuteronomy 24:7), "and he abused (hitaamer) him" - they, may their memory be blessed, explained (Sanhedrin 85b), that [it means that] he brought him into his domain and made him serve.