What is the basis for ruling that the Iddah for an Umm Walad upon her master's death is three menstrual cycles?
General Chapter
Al-Mughni
Book of Waiting Periods ('Iddah)
Primary text
The ruling that the Iddah is three menstrual cycles is based on the argument that she is free and requires purification ('Istibra'), just like a divorced free woman. This view is attributed to 'Ali, Ibn Mas'ud, Al-Nakha'i, and the companions of Abu Hanifa.
Supporting text
The refutation states that the analogy is invalid because she is neither divorced nor in the position of a divorced woman. The true purpose of this purification is the removal of ownership related to slavery, which mandates one cycle for women who menstruate, similar to other freed and owned women, and it is a purification for non-wives or those without marital suspicion.