The root of their disagreement lies in whether zakāh is an act of worship or a fixed financial right in the property of the rich that belongs to the poor.

Whoever views it as a right belonging to the poor says: “No zakāh is due on the assets of a debtor, because the creditor’s claim precedes the claim of the poor in time, and in truth the property is the creditor’s, not that of the person in whose hand it now rests.”

By contrast, those who hold that zakāh is an act of worship respond: “It is obligatory upon anyone who possesses wealth, for possession is the very condition that renders a person legally answerable and signals the duty’s onset, whether or not he is in debt. Here two rights collide—one that belongs to Allah and one that belongs to a human being—and Allah’s right is more deserving of fulfillment.” Even so, the overall aim of the Sacred Law appears closer to waiving zakāh for the insolvent debtor, in light of the Prophet’s—peace and blessings be upon him—statement concerning it: “It is charity taken from their wealthy and returned to their poor,” and the debtor is not wealthy.

As for those who differentiate between grain and non-grain, or between readily liquid assets and others, I know of no clear proof for their position. Abū ʿUbayd used to say: “If it is not publicly known that a man is in debt, nothing is taken from him.” This is not a disagreement with those who drop zakāh on account of debt, but rather with those who maintain that a person’s claim of being in debt is accepted just as his claim about the amount of his wealth is accepted.

They likewise disputed the zakāh of debts owed to a person—funds that remain merely in the debtor’s liability and not in the owner’s hand. One group said: “No zakāh is due on such a debt, even after it is collected, until the recipient has held it for a full lunar year.” This is one of the two opinions reported from al-Shāfiʿī, and it is also the view—or at least the logical extension—of al-Layth.

Another group held: “When he receives the money, he must pay zakāh for all the past years.”

Mālik said: “He pays one year’s zakāh only, even if the money remained with the debtor for many years, provided the original debt arose from an exchange. If it arose without consideration—such as through inheritance—he begins counting a new year from the time he receives it.” The Mālikī school offers further detail on this issue.

Under the same heading falls their disagreement over the zakāh of fruits borne by trees whose roots are held in waqf, and over the zakāh of leased land: on whom does the duty fall for what the land produces—the owner of the land or the cultivator? Related to this, they differ over kharāj land that passes from the people who pay kharāj to Muslims who pay the ʿushr, and over ʿushr land that passes to those who pay kharāj, i.e., non-Muslim subjects. All these situations seem to stem from the fact that the ownership involved is deficient.

As for the first issue—the zakāh of fruits whose trees are waqf—Mālik and al-Shāfiʿī both required zakāh. Makḥūl and Ṭāwūs said that no zakāh is due. Some jurists distinguished: if the waqf is dedicated to the poor in general, they did not impose zakāh; if it is assigned to specific individuals, they required it, but not when it is for the poor at large.