Is the option to rescind a sale due to a defect exercisable immediately or over time?
Chapter on Selling the Musarrah (Animal with milk retained in udder)
Al-Mughni
Book of Sales
Primary text
The option to rescind a sale due to a defect is exercisable over time (at leisure). If the defect is discovered and the rescission is delayed, the option does not lapse until an action indicating consent to the defect occurs. Abu al-Khattab mentioned this view. The basis for this is that the option is intended to avert an established harm, therefore it must be exercisable over time, analogous to retribution (Qisas). The mere retention of the item is not necessarily indicative of consent to the defect.
Supporting text
There are two reported narrations regarding this. One holds that the option is exercisable over time. The second view, which is the opinion of Al-Shafi'i, holds that the option must be exercised immediately (upon discovery). If the option is delayed while the possibility of rescission exists, the option lapses because the delay implies consent, similar to disposing of the item.