It was narrated that ʿUmar, while walking one night along one of the lanes of Madinah, heard a woman calling out and saying, “Is there a way to obtain wine so that I may drink it, or a way to reach Naṣr ibn Ḥajjāj?” When morning came, he went to Naṣr and found him to be the handsomest of people in face and the finest of them in hair. He said to him, “This is a firm order from the Commander of the Faithful: you must cut your hair.” So he cut some of his hair.
Chapter on the Rulings of Ḥisbah
Ḥisbah is commanding what is right when its neglect becomes apparent, and forbidding what is wrong when its commission becomes apparent. Although every Muslim may perform this duty, there are nine distinctions between the muḥtasib and the volunteer.
First: The obligation is specifically incumbent upon the muḥtasib by virtue of his official authority, whereas for others it falls under the collective obligation.
Second: The muḥtasib’s undertaking of this duty is among the responsibilities of his office, and he may not occupy himself with something else instead of it. The volunteer’s undertaking of it is a supererogatory act, which he may leave in order to occupy himself with something else.
Third: The muḥtasib is appointed to receive complaints brought to him in matters requiring intervention, whereas the volunteer is not appointed as an authority to whom complaints may be brought.
Fourth: The muḥtasib is obliged to respond to anyone who brings such a complaint, whereas the volunteer is not obliged to respond to him.
Fifth: He must investigate apparent acts of wrongdoing in order to forbid them, and examine what has been neglected of the apparent forms of right in order to command that they be upheld. Others who volunteer for this duty are under no obligation to do so, nor to conduct such investigations.
Sixth: He may appoint assistants to help him in forbidding wrong, because it is a task for which he has been appointed and which he is specifically enjoined to undertake, so that he may be more forceful in it and better able to carry it out. A volunteer may not appoint assistants for this purpose.
Seventh: He may impose taʿzīr for apparent acts of wrongdoing, but may not go beyond them to impose the fixed punishments. A volunteer may not impose taʿzīr for an act of wrongdoing.