The ruling when a master specifies forgiveness of the middle installment payment (Awsat).
General Chapter
Al-Mughni
Book of Mukātaba (Contractual Manumission)
Primary text
If the master says, 'Forgive him his middle installment,' and there is only one middle one, the bequest is designated to it. This occurs if the installments are equal in value and term, and the number is odd, where the middle one numerically is chosen (e.g., the third out of five, or the fourth out of seven). If the number is even and the values differ (e.g., some 100, some 200, some 300), the one valued at 200 is the middle one and is designated. If the values are equal but the terms differ (e.g., two due in one month, one in two months, one in three months), the one due in two months is designated as the middle one in terms.
Supporting text
If the three criteria (value, term, number) are met in a single installment, it is designated. If there are different middles for value, term, and number that conflict, the choice belongs to the heirs, and they may forgive whichever they wish. If the heirs and the Mukatab disagree on the master's intent, the word of the heirs, coupled with their oaths that they do not know the master's intent, is accepted, and the designation then falls to them. If there are two middle options, the heirs choose one. If the number is odd, there is one middle. If the number is even (like four or six), the middle constitutes two options.