As for the other forms of contract, it is possible to assimilate them to sales, for they share with sales the element of preoccupation; nevertheless, they are seldom concluded at that particular time, unlike sales.

With regard to the rest of the prayers, they might likewise be attached to the Friday prayer by way of recommendation for one who is awaiting the prayer’s appointed time; but once that time has arrived, the attachment would become one of prohibition. To the best of my knowledge, however, no one has explicitly advanced this view.

For this very reason Allah praised those who forsake trading when the time for prayer comes, saying:
“Men whom neither commerce nor sale distracts from the remembrance of Allah, the establishment of prayer, and the payment of alms.” (al-Nūr 37)

Now that we have established the general causes that render sales invalid, let us turn to the causes and conditions that validate them. This is the second part of our general study of sales.

Part Three
Causes of Validity in Unrestricted Sales
Chapter One
On the Formulae of Selling and Buying
Section Two

In sum, the causes and conditions that validate a sale are the very opposite of those that vitiate it, and they fall into three categories:

1. Matters relating to the contract itself;
2. Matters relating to the subject-matter of the contract;
3. Matters relating to the contracting parties.

Accordingly, this part comprises three chapters.

Chapter One: Concerning the Contract
A contract is not valid unless it is concluded with explicit past-tense expressions of sale and purchase, such as the seller’s saying, “I have sold to you,” and the buyer’s saying, “I have bought from you.”

If someone says to the seller, “Sell me your merchandise for such-and-such,” and the seller replies, “I have sold it,” Mālik holds that the sale has been effected and is binding upon the inquirer unless he presents a valid excuse. Al-Shāfiʿī, on the other hand, maintains that the sale is not complete until the buyer adds, “I have bought.”

Likewise, if the buyer says to the seller, “For how much do you sell your merchandise?” and the seller answers, “For such-and-such,” whereupon the buyer declares, “I have bought it from you,” the jurists disagree whether the sale is binding immediately or only after the seller says, “I have sold it to you.”

According to al-Shāfiʿī, a sale may be concluded with either explicit wording or with indirect wording; I know of no statement from Mālik on this point. In the Shāfiʿī school, mere hand-to-hand exchange without any verbal formula does not suffice.

To the best of my knowledge there is no disagreement that the offer and acceptance which together create binding force must occur without a delay that lasts until the parties disperse. What I mean is that if the seller says, “I have sold my merchandise to you for such-and-such,” and the buyer remains silent until they leave one another, then later says, “I have accepted,” the seller is not bound by that.

The jurists differ as to the moment at which bindingness is achieved. Mālik, Abū Ḥanīfah and their followers, along with a group of the scholars of Madinah, say that a sale becomes binding within the session once the verbal exchange takes place, even if the parties have not yet separated. Al-Shāfiʿī, Aḥmad, Isḥāq, Abū Thawr, Dāwūd, and Ibn ʿUmar among the Companions—may Allah be pleased with them—hold that the sale is not binding until the parties part company; so long as they remain together, the sale is neither binding nor even concluded. This is also the view of Ibn Abī Dhiʾb and a group of the scholars of Madinah, Ibn al-Mubārak, Sawwār the judge, Shurayḥ the judge, and many of the Successors and others. It is narrated from Ibn ʿUmar and Abū Barzah al-Aslamī among the Companions, and no Companions are reported to have disagreed with them.

The main evidence of those who impose the condition