Likewise, in matters of custom the Messenger of Allah, peace and blessings be upon him, said, “The side-niche grave is for us, and the trench grave is for others.” It is also recommended that Muslim graves face the Kaʿbah so that they are clearly distinguished from the graves of the unbelievers. Burial itself is a permissible customary practice, yet the divine laws differ over the way it is carried out, and within it are elements of worship as well.
Wearing sandals in the prayer, for example, is both worship and habit, whereas removing them during the prayer was a prescription given to Moses, peace be upon him. The same applies to staying away from menstruating women and similar rulings in which we share the basic practice with earlier communities but differ from them in its particulars.
The second division concerns matters that were once prescribed but have been completely abrogated—such as the Sabbath, or the obligation of a particular prayer or fast. It is obvious that we are forbidden to imitate them in such things, whether the practice was obligatory for them, thereby making it worship, or forbidden for them, thereby placing it among customary matters. Accordingly, a person may not abstain, as a devotional act, from eating animal fat or the meat of any creature with a single hoof. The same holds for matters that combine both worship and habit, namely the festivals that were legislated for them. A legitimate festival brings together worship—prayer, remembrance, charity, or sacrifice—and custom, that is, the social activities observed on that occasion.