פירוש על קידושין 35:15

The question is—why is this a difference between male and female slaves? Why not also force male slaves to be redeemed due to family disgrace? The answer is that the male slave can go sell himself again, whereas a female slave cannot be sold twice. So once we (the community) redeem her against her will, she can no longer be sold into slavery.
We should note that this opinion of Abaye and indeed of the other sages shows just how deeply discomforted they were by the very notion of a father selling his daughter into slavery.

According to the first opinion, once a man marries off his daughter, if she is divorced or widowed while still young, he can marry her off again. If he sold her to be a slave and she was freed while still young, he can sell her off again. And if he sold her to be a slave, and she was freed while still young, he can still marry her off. But if he sold her to be a wife, he cannot sell her later to be a slave. R. Shimon is more restrictive and rules that once sold into servitude, she cannot be sold again.

The Torah states that if he did not designate her to his son as a wife or marry her himself, he must set her free. He cannot sell her to non-Jews. The phrase used for “deal deceitfully” is “bevigdo bah.” Beged (bg”d) is the root for “dealing deceitfully” but it is also the root for the word “clothing.” R. Akiva reads the word as if it means “clothing”—once the master has “spread his clothing over her,” i.e. he has married her, can no longer sell her. Once she was married, the father can no longer sell her. R. Eliezer reads the word differently—since the father dealt deceitfully with her by selling her the first time, he can no longer sell her.