Is *Umm Walad* (a female slave who bore her master's child) freed upon being married off by her master and then the husband dies?

Primary text

If a master marries off his *Umm Walad*, and the husband subsequently dies, she is immediately manumitted (freed). No post-marriage waiting period (*Istibra'*) is required for her former master. This is because she is forbidden to the former master (due to the marriage) and is not his sexual property (*farash*); rather, she is the sexual property of the husband. Therefore, an *Istibra'* is not obligatory for someone who is not her *farash*. Furthermore, the master did not marry her off until she had already undergone an *Istibra'* (as it is not permissible for him to marry her off before an *Istibra'*).