letting it grow thick or cultivating flamboyant mustaches is not permissible, for it contradicts the Prophet’s ﷺ instructions: “Trim the mustaches,” “Closely shave the mustaches,” “Clip the mustaches,” and, “Whoever does not take from his mustache is not one of us.” These four expressions are all found in authentic hadiths from the Prophet ﷺ, and the last wording—“Whoever does not take from his mustache is not one of us”—contains a severe threat and an emphatic warning. This obliges every Muslim to beware of whatever Allah and His Messenger have forbidden and to hasten to fulfill whatever Allah and His Messenger have commanded.

From this you also learn that growing the mustache long and adopting ostentatious styles is a sin and an act of disobedience. Likewise, shaving the beard or cutting it short is among the sins and acts of disobedience that diminish and weaken faith, and through which one fears the descent of Allah’s wrath and punishment.

The aforementioned hadiths further indicate that lengthening the mustache and shaving or trimming the beard resemble the practices of the majūs (Zoroastrians) and the mushrikīn (polytheists), and imitating them is an evil deed that is not permissible, for the Prophet, peace and blessings be upon him,