and the parties’ ensuing delivery and receipt, and similar acts, constitute performance of the contracts, just as carrying out what one has been commanded to do constitutes compliance in matters governed by the Sacred Law.

Taking possession may be valid or invalid, just as a contract may. A contract is subject to legal rulings, just as taking possession is. Therefore, if taking possession is determined by people’s customs and customary practices, without any fixed standard that applies equally to everyone in every circumstance and at every time, the same applies to contracts. To formulate this precisely, one would say that contracts are one of the two kinds of transactions. Recourse concerning them is therefore to people’s customary practice, just as with the other kind.

Related to this is the principle that permission understood from customary practice—whether concerning permission to use something, the transfer of ownership, or acting by way of agency—is equivalent to verbal permission. Both agency and permission to use are established by any words or actions that indicate them, and knowledge that the entitled party consents takes the place of that party’s express declaration of consent.

On this basis may be understood the Prophet’s (peace and blessings be upon him) giving the Pledge of al-Ridwān on behalf of Uthmān ibn Affān while he was absent, and his bringing the men of the Trench into the homes of Abū Talha and Jābir without seeking their permission, because he knew that both consented to it. Likewise, when a butcher invited him (peace and blessings be upon him) as one of a party of six, another man followed them; he did not let that man enter until he had obtained permission from the butcher who had extended the invitation. Similarly, it is reported of al-Hasan al-Basrī that when his companions entered his home and ate his food, he said, “You have reminded me of the character of a people who have passed away.”

The same is the meaning of Abū Jaʿfar’s statement: “Brothers are those who insert