His words, “Marriage is valid,” mean that a marriage contract concluded after the second call to prayer for Friday is valid, because Allah prohibited only trade; He did not prohibit marriage. Moreover, a sale is a transaction of exchange that occurs frequently among people, unlike marriage.
His words, “and all other contracts” (1): the apparent meaning of his statement is that pledging collateral, providing a guarantee, giving a loan, leasing, confirming a sale subject to an option, mutually rescinding a sale, and so forth are all valid. Indeed, all contracts are valid.
However, what is correct is contrary to the author’s view, may Allah have mercy on him: all other contracts are prohibited just like a sale. Allah mentioned trade only because of the circumstances that occurred: when the caravan arrived from Syria, the Companions, may Allah be pleased with them, went out and began trading with it (2). Thus, restricting the ruling to sales is only in consideration of the actual event; otherwise, everything that distracts from attending the Friday prayer is like a sale, with no distinction between them.
In this issue, the author adopted the position of the literalists: restricting oneself solely to the wording of the text, namely His saying: “and leave off trade.”
The correct view, then, is that all contracts are invalid and unlawful. No exception is made for marriage, loans, pledges, or anything else. Yes, someone may perhaps say that gratuitous contracts, such as a gift, do no harm, because they do not