What is the legal ruling concerning a master freeing his slave contingent upon the slave paying a deferred sum?

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The contractual arrangement where a master frees his slave upon the slave's promise to pay a deferred sum is termed Kitabah (manumission by installment). The basis for the legality of Kitabah is established by the Quran, the Sunnah, and the consensus (Ijma) of the Ummah. The Quranic evidence states: "And those who seek a contract for what your right hands possess, from among those whom your right hands have taken, seek a contract from them if you know there is good in them" (Quran 24:33). Concerning the Sunnah, it is narrated from Umm Salamah that the Prophet (peace be upon him) said regarding a female slave who has a contract of manumission: "If one of you has a mukatabah (female contracted slave), and she manages to pay what is due upon her, she must observe the hijab from him (her master)." Furthermore, it is narrated from Sahl ibn Hunaif that the Prophet (peace be upon him) said: "Whoever assists a debtor, a warrior in battle, or a contracted slave in his contract (Kitabah), Allah will shade him on the Day when there is no shade but His." The entire community has reached a consensus on the legitimacy of Kitabah.