Najsh refers to a person’s raising the price of an item while having no intention of buying it himself, his aim being to profit the seller and harm the genuine purchaser. The jurists differed about the legal effect when such a sale actually takes place.

• The Ẓāhirī scholars held that the contract is invalid.
• Mālik said it is like a hidden defect: the buyer has an option; if he wishes he may rescind, and if he wishes he may keep the purchase.
• Abū Ḥanīfah and al-Shāfiʿī maintained that although the perpetrator is sinful, the sale itself remains valid.

The root of the dispute is whether a prophetic prohibition automatically renders the prohibited transaction void. If the prohibition concerns something intrinsic to the contract, some argue that it necessitates cancellation, whereas others say it does not. The majority take the view that when the prohibition addresses a defect within the transaction—such as usury or excessive uncertainty—it entails invalidity; but if the reason is external, it does not.

A comparable case is the Prophet’s—peace and blessings be upon him—prohibition of selling water. In one wording he said:

“He forbade the sale of surplus water lest pastureland be withheld.”

Abū Bakr ibn al-Mundhir stated: “It is firmly established that the Messenger of Allah—peace and blessings be upon him—‘forbade the sale of water and forbade the sale of surplus water lest pastureland be withheld,’ and said: ‘Access to a well must not be denied, nor its water sold.’”

Scholars have differed over the interpretation of this prohibition. A group understood it in the broadest sense, declaring that the sale of water is never permissible—whether it comes from a well, a pool, or a spring, and whether the land is privately owned or not—except that if the source is owned, the owner has first claim to what he himself needs from it. In this vein Yaḥyā ibn Yaḥyā said, “There are four things I do not think may be withheld: water, fire, firewood, and pasture.”

Others restricted these ḥadiths on the basis of established legal principles, namely that a person’s property is unlawful to take except with his willing consent, as the Prophet—peace be upon him—said, and on which consensus has been reached. Those who qualified the texts differed as to how that qualification applies.

• Some explained that the prohibition concerns a well shared by two partners: when one irrigates his land on his appointed day and finishes watering his crop before the day ends, he must not prevent his partner from using what remains of the water for the rest of that day.

• Others said it applies when someone’s cultivation depends on a well that subsequently collapses, while his neighbor has surplus water; the neighbor may not withhold that surplus until the well is repaired. These two explanations are close in meaning. Their basis is to interpret the unqualified ban in the two ḥadiths by reference to the qualified clause: the Prophet first prohibited the sale of water in absolute terms and then prohibited withholding surplus water, so they concluded that it is the surplus that may not be withheld or sold.

As for Mālik, the core of his school is that whenever water lies within land that is privately owned and protected, it belongs to the landowner, and he is entitled to sell it.