is applied in the opposite direction: when several benefits coincide and not all of them can be secured, one gives priority to the highest, then the next in rank. In other words, with benefits one pursues the superior, whereas with harms one accepts the lighter and the lesser.

Further lessons from this ḥadith include:

• The obligation to cleanse the mosque, a communal duty (fard kifāyah). The Prophet ﷺ said, “Pour a bucket of water over his urine.” Accordingly, whoever sees an impurity in the mosque must either remove it himself or inform those responsible for the mosque so they can do so.

• The place of prayer must be pure. A worshiper is required to ensure the purity of his garments, body, and prayer-spot—whether it is bare ground, a mat, or anything else. The essential point is that the place where he prays be clean.

• To purify earth, it suffices to pour water over the impurity once; when the water permeates the spot, it is clean. If, however, the impurity has a solid mass, such as excrement or dung, that mass must first be removed, after which the area is purified by pouring water over it.

• Water is necessary for removing impurity, as indicated by the Prophet’s words, “Pour a bucket of water over his urine.” Hence, according to the majority of scholars, impurity is not removed by anything other than water.

• The sounder view, however, is that impurity may be removed by whatever eliminates it—water, gasoline, or any other effective agent. The Prophet ﷺ instructed that water be poured over the urine only because that is the quickest way to cleanse the spot. Otherwise, one could leave it; with wind and sunlight the impurity would eventually disappear and the ground would become pure, but using water is faster and easier.