Commentary for Exodus 21:11

ואם שלש אלה לא יעשה לה means IF HE DO NOT one of THESE THREE UNTO HER. What are these three? He should designate her to himself as his wife, or to his son, or allow her a deduction from the ransom so that she may go free (Mekhilta d'Rabbi Yishmael 21:11:1). This man, however, has neither betrothed her to himself, nor to his son, and she herself does not possess the entire sum paid for her originally that she might buy herself out, therefore shall she go out free without money.

ואם שלש אלה לא יעשה לה, If he fails to do these three things for her, etc. The three are 1) marrying her, שארה; 2) providing her with a clothing allowance, etc., כסותה; 3) maintaining marital relations with her at designated intervals, עונתה; the Torah stresses the word אלה, these, so as to exclude previous conditions such as the need to betrothe her. ויצאה חנם אין כסף, she may leave for nothing without money. Both master and son have lost their authority over this girl; they cannot force her to serve the balance of the six years her father contracted for, or until she displays signs of puberty. Rather the master has to give the girl a document releasing her if he does not decide to consummate the betrothal. The words "without money," mean that there is no need for money to change hands whereas there is a need for a divorce document releasing her as the Torah considered the girl as betrothed to her master ever since her father had sold her. Our sages in the Mechilta add that the words אין כסף also mean that whereas the maidservant does not have to compensate her master financially if he failed to meet the conditions mentioned, she can also gain her freedom by merely attaining the age/or signs of puberty. All of these rulings are of Sinaitic origin, independent of any allusions in the text.

ואם שלש אלה, that he neither wants to marry her himself, nor have her marry his son, nor allow her to buy herself out of her contract,