Albert Barnes Commentary Exodus 21:11

"And if he do not these three things unto her, then shall she go out for nothing, without money." — Exodus 21:11 (ASV)

If he does not do these three to her - The words express a choice of one of three things. The man was to give the woman, whom he had purchased from her father, her freedom, unless:

1. he arranged for her to be redeemed by a Hebrew master (Exodus 21:8);
2. he gave her to his son and treated her as a daughter (Exodus 21:9); or
3. in the event of his taking another wife (Exodus 21:10), unless he allowed her to retain her place and privileges.

These rules (Exodus 21:7–11) are to be regarded as mitigations of the then-existing customs of concubinage.