Is it permissible for a master who has decreed conditional manumission (Tadbir) for his slave to subsequently enter into a contract of manumission through correspondence (Kitaba) with that slave?

Primary text

The decree of manumission through Tadbir is valid even after the master has entered into a contract of Kitaba with the slave. This ruling is affirmed by Ahmad ibn Hanbal. It is also the position of Ibn Mas'ud, Abu Hurayrah, and Al-Hasan. The basis for this is reported through Mujahid concerning a woman of the Quraysh who decreed Tadbir for her female slave and then sought to enter a Kitaba contract. Abu Hurayrah instructed that the Kitaba proceed; if the slave fulfilled the payments, she would be manumitted by the Kitaba, and if an event occurred to the master (death) before completion, the Tadbir would effect manumission. Both Tadbir and Kitaba are means to manumission; if one is a manumission by a condition, it does not preclude the Kitaba, similar to conditional manumission upon entering a dwelling. If Tadbir is viewed as a bequest, it also does not prevent Kitaba, just as if the master had bequeathed manumission and subsequently contracted Kitaba. Since both are causes for manumission, neither should prevent the other, analogous to the manumission of a Mukatab (one engaged in Kitaba).