The second category of knowledge comprises all additional legal rulings required by the Muslim community as a whole but not by every individual in person—such as the rulings on sales and commercial transactions, on endowments, inheritance, and bequests, on marriage, and on criminal offenses. These matters are indispensable for the ummah, yet it is not obligatory for every single Muslim to study them. If a sufficient number of scholars acquire this knowledge so that the community’s needs for adjudication, issuing fatwas, teaching, and the like are met, that suffices. This is what is called wajib al-kifayah (a collective obligation): if enough people undertake it, the sin is lifted from the rest, but if everyone neglects it, they are all blameworthy.

The community must therefore have individuals who learn this category because it needs them; nevertheless, it cannot be said to each and every person, “You are required to master these chapters,” for that is not feasible for everyone. The duty is confined to those within the ummah who possess the ability and the means, and once a segment of the community gains this knowledge the obligation is discharged. This differs from the first category, for which every person is personally responsible, since these acts cannot be carried out properly without knowledge. Hence the Shaykh said, “It is obligatory upon us,” and he did not say, “It is obligatory …”