If he designates her for his son, he shall deal with her as with a daughter.
The first verse is the general title of the laws contained in this and the two following chapters, some of them relating to the religious worship of God, but most of them relating to matters between man and man. Their government being purely a Theocracy, that which in other states is to be settled by human prudence was directed among them by a divine appointment...
Commenting on Exodus 21:1-11
And if he have betrothed her unto his son,.... Not caring to betroth and marry her himself, as being more suitable in age for his son than for himself: he shall deal with her after the manner of daughters; as if she was his daughter, and give her a dowry: or the son shall treat her after the manner the daughters of Israel are treated...
LAWS FOR MAIDSERVANTS. (Exo. 21:7-36) if a man sell his daughter--Hebrew girls might be redeemed for a reasonable sum. But in the event of her parents or friends being unable to pay the redemption money, her owner was not at liberty to sell her elsewhere.
Commenting on Exodus 21:7-36