The hadiths cited above make it clear that growing and leaving the beard is obligatory, while shaving or trimming it is forbidden. This is because the basic rule regarding the Prophet’s commands is that they entail obligation, and the basic rule regarding his prohibitions is that they entail forbiddance—unless evidence proves otherwise. This is the position relied upon by the scholars.

Allah, Exalted is He, says: “Whatever the Messenger gives you, take it; and whatever he forbids you, refrain from it. And fear Allah, for Allah is severe in punishment” (al-Hashr 59:7). He also says: “So let those who oppose his command beware, lest a trial befall them or a painful punishment seize them” (al-Nūr 24:63).

Imam Aḥmad (may Allah have mercy on him) explained that “the trial (fitnah) is polytheism: a person who rejects any part of the Prophet’s instruction may have deviation placed in his heart and thus be ruined.” Nowhere in the Qur’an or the Sunnah is there anything to indicate that the command found in these hadiths and others like them is merely recommended.

As for the report transmitted by al-Tirmidhī from Abū Hurayrah (may Allah be pleased with him) stating that the Prophet ﷺ used to take from his beard both in length and breadth, the scholars have judged it invalid, because its chain of transmission includes a man named ʿUmar ibn Hārūn, who is accused of fabricating hadiths.