Chapter on the Right of Option (khiyār)
Introduction
Khiyār, pronounced with a kasrah on the khāʾ, is an ism masdar derived from ikhtāra yakhtāru; it is not the actual masdar. An ism masdar conveys the same action as the masdar but does not contain all the letters of the verb; its form drops some of those letters, both in pronunciation and in estimation.

In the Sharīʿah, khiyār in sales and similar contracts means seeking the better of two courses: here, either rescinding the sale or letting it stand. The khiyār of the session (khiyār al-majlis) is established by sound hadiths, and sound analogy supports it as well.

Disagreement among the scholars
The scholars differed over whether a sale remains valid during the option period. The majority—Shafiʿis and Hanbalis—hold that it does, supported by clear evidences. The Mālikis, however, deem it invalid and excuse their non-implementation of the hadiths with weak arguments, among them that it runs counter to the practice of the people of Medina. The majority have replied to those objections.

Its wisdom
Ibn al-Qayyim said: The Lawgiver upheld the khiyār of the session in sales out of wisdom and concern for both contracting parties, so that the full mutual satisfaction required by Allah in His words, “unless it be trade conducted by mutual consent among you” (Qur’an 4:29), may truly be achieved. A contract is often struck suddenly, without careful thought or price comparison, so the perfection of this Sharīʿah decreed a span of time during which the two parties may reflect, reconsider, and each may retrieve what he has overlooked.