Mālik held that the sale or purchase concluded by a person who is drunk is impermissible. If such a person seeks to undo the transaction, he must swear by Allah that he had no awareness whatsoever at the very moment he sold or bought—during the period before the contract would have become binding upon him.

Ibn al-Qāsim said: Should an apostate sell or buy during the days set aside for his repentance, or while he remains in that state, the transaction is annulled; and if he is executed, those who dealt with him have no claim. If he returns to Islam, however, any debt he incurred remains enforceable. Even if people transact with him, assuming him to be a Muslim or a protected non-Muslim, when in fact he had already apostatised, their sale is not cancelled; liability is met from his estate.

The ruling on the apostate is treated in Kitāb al-Siyar (the Book of Military Conduct). The ruling on the spendthrift, his sales and other dispositions—together with the guardian’s sale or purchase involving the ward’s property and a father’s purchase from himself of his minor child’s assets—will all be found in Kitāb al-Waṣāyā (the Book of Bequests), if Allah wills.