The Messenger of Allah ﷺ also forbade certain matters in which the corruption is concealed because they inevitably lead to manifest corruption. One such case is riba al-faḍl (surplus usury), whose underlying wisdom may not be immediately obvious. The harm caused by gharar (undue uncertainty) is less than that of riba, which is why the Law grants a concession wherever genuine need arises. Thus it is permitted, for example, to sell a building even though its foundations are not known; to sell a pregnant or lactating animal even though the pregnancy or the milk is uncertain; and to sell fruit once its soundness has begun to show, even though the elements that complete its ripening have not yet materialised. These examples make it clear that a slight, incidental degree of gharar is tolerated when unavoidable, whereas it is not tolerated elsewhere.

As for riba, when people required the ʿarāyā arrangement, a dispensation was granted to sell on the basis of estimation (kharṣ), yet definite inequality was not allowed. Rather, equality determined by estimation was sanctioned only for the small amount to which necessity points—the measure of a niṣāb, that is, five wusq or less.

In the field of sales Mālik’s methodological principles are sounder than those of others, and Imam Aḥmad generally agrees with him: both declare riba unlawful and enforce its prohibition with full strictness, blocking every avenue that leads to it even when no stratagem is involved.

In sum, the scholars of Medina and the jurists of hadith impose a firm, well-considered ban on every form of riba, mindful of the objectives and foundations of the Sharīʿah. Their stance reflects what is reported from the Companions and is supported by the purport of the Qur’an and Sunnah.

With regard to gharar, the strictest views are those of Abū Ḥanīfah and al-Shāfiʿī, for they include under this heading types of transactions that other jurists do not—for instance, the sale of grain and fruit while still in their husks, such as broad beans, walnuts and almonds in the shell, and grain still in its ear. According to al-Shāfiʿī’s later opinion, all of that is impermissible.

Mālik’s position here is the best: he allows the sale of these items and of everything people need or whose element of gharar is slight. He even permits the bulk sale of vegetable beds and the sale of produce hidden beneath the soil, like carrots and radishes.

Aḥmad is close to this view. Ibn ʿAqīl transmits two opinions from him on the matter, the second of which agrees with Mālik in allowing it, and that view is consistent with Aḥmad’s legal foundations.