Is it permissible to state the payment period without dividing it into installments, such as 'pay it in ten years'?
General Chapter
Al-Mughni
Book of Mukātaba (Contractual Manumission)
Primary text
It is not permissible to state 'pay it in ten years' or 'until ten years,' because this constitutes a single installment, which is generally disallowed unless one permits the kitabah on a single installment.
Supporting text
If one specifies that 'some of it is paid at the midpoint and the rest at the end,' it is not permissible because the 'some' (al-ba'd) is ambiguous, referring to a small or large amount.