Reference: http://mufti.af.org.sa/ar/content/خالفوا-المجوس-قصوا-الشوارب
Question: Is the one who shaves his beard off sinful? Because I heard someone saying “the one who practices the Sunnah is rewarded, and the one who does not is not sinful.”
Response: Shaving off the beard is prohibited, and letting the beard grow is obligatory. The Prophet ﷺ said:
…and:
So the Sunnah is to leave the beard [to grow], and not to touch (shave) it. And if he has spoken about this obligation to be a Sunnah, then this [here] does not mean [both the act of] doing and leaving are equal. No, rather shaving off the beard is sinful. That is because opposing the Sunnah of Muhammad ﷺ means to oppose his guidance and his way. And that which should not be understood here by the [use of the term] Sunnah is that “the one who practices it is rewarded, and the one who does not is not sinful.”
