Definition of "Al-bai‘ al-batil"
An agreement of sale which is unlawful in respect of its substance and description. For example, an agreement of sale concluded by a lunatic or a minor is batil since it does not possess substance of the agreement, which is the proposal and acceptance by a sane or major person. Similarly, an agreement to sell a dead body or alcohol is not lawful since it involves exchange of mal for something valueless (ghair mutaqawwam). See also al-bai‘ al-fasid.