Or HaChaim on Exodus 21:8/אור החיים על שמות כ״א:ח׳

1 אשר לא (ו) יעדה והפדה, who has espoused her to himself, then he shall let her be redeemed. The reason the word lo is written with the letter א while it is read as if it were spelled with the letter ו, is explained in Kidushin 19 to mean that her espousal must meet with her approval. The master cannot marry her against her wishes. The Talmud derives it from the word יעדה. The Torah therefore begins the verse with "if she is displeasing in the eyes of her master" as describing a hindrance to the marriage which originates with the master. Concerning a hindrance due to the girl, the Torah writes אשר לא יעדה, to indicate that she was the party who did not agree. As a result, i.e. if either party declines to marry the other, והפדה, the legislation of facilitating her release by deducting time not served becomes applicable. If the parties agree to marry, there is no cause for the girl's prior release.

2לעם נכרי, to another party, etc. The Torah has to legislate this in order to inform us that though the father has a right to sell his daughter, he does not have the right to sell her לעם נכרי. The words לא ימשול למכרה "he has no auhority to sell her," indicate that if the father sold her without a view to eventual marriage by her master or his son, such a sale is invalid because he has betrayed the girl's trust. The moment the father or the master has betrayed his trust he has forfeited every right to buy or sell this girl.

3Another aspect discussed in Kidushin 19 is the right of the father to sell his daughter to a master who is forbidden to marry her by Jewish law, such as a widow to a High Priest or a divorcee to an ordinary priest. By precluding the father's right to sell his daughter to עם נכרי, a member of an alien people, the Torah implies that a sale to the above-mentioned categories is legally valid seeing the buyer is a Jew.