But as for goods that are of one kind and of equal value, the sale is valid, because buying them by these methods does not involve the forbidden ignorance.
6. From this the jurists inferred the invalidity of purchasing an unknown item and the invalidity of a blind person buying something whose only avenue to knowledge is sight, for that leads to gharar (uncertainty).
7. As for an absent item, its sale is valid if it is so fully described that the description removes any ignorance, like the detailed specifications required in a salam sale. If, when the buyer receives it, he finds that it does not match the stipulated description, then: if it was a specifically designated item, the contract is void; but if it was an item owed in the seller’s liability, the contract remains valid and the seller must provide what fulfils all the specifications stipulated in the contract.
8. Al-Nawawī said: “Know that mulāmasah, munābadhah, and the like—although expressly mentioned—fall under the general prohibition of sales involving gharar; they were singled out only because they were well-known transactions of the pre-Islamic period.” He also said: “The prohibition of sales that involve gharar is a great foundational principle of commercial law; countless issues fall under it.” Ibn ʿAbd al-Barr said: “The basis of this entire chapter is the ban on gambling and risk-taking, for that is the maysir the Law forbids.”
9. It is thus clear that everything prohibited in this ḥadīth goes back to the second criterion mentioned earlier.
Second ḥadīth (1)
Abū Hurayrah—may Allah be pleased with him—reported that the Messenger of Allah ﷺ said: “Do not intercept caravans on the way; none of you must sell over the sale of his brother; do not engage in najsh (artificially bidding up the price); let no town-dweller sell on behalf of a desert-dweller; and do not tie the udders of sheep (2). Whoever buys such an animal has a choice between two alternatives after milking it: if he is pleased with it, he keeps it, and if he is displeased, he returns it together with a sāʿ of dates.”
In another wording: “He has the option for three days.”
Third ḥadīth
ʿAbd Allāh ibn ʿAbbās—may Allah be pleased with them both—said: “The Messenger of Allah ﷺ forbade intercepting caravans on the way and forbade a town-dweller from selling on behalf of a desert-dweller.”