The mukātab owns his earnings, the benefit of his labor, and may enter into any transaction that improves his property. Any child she bears after the kitābah contract shares her status, just like the offspring of an umm walad or of a mudabbara (a slave set free through tadbīr).

Section
On Umm Walad (mothers of children)

If a free man fathers a child with his own female slave, with his son’s female slave, or with a female slave in which either of them owns a share, and she delivers an offspring that shows any trace of human form, even faintly, she becomes his umm walad. She is emancipated from the entirety of his estate upon his death, even if she had killed him.

Her rulings are those of an ordinary slave in matters such as intercourse, service, and hiring out. They do not apply, however, to transactions that transfer ownership or are intended for that purpose—such as sale, endowment, or pledge—and the like.