What is the ruling on leaving the mustache and cutting the beard?

The questioner : Okay, Shaykh: What is the ruling on leaving the mustache and cutting the beard?

The Shaykh : This is not permissible. It is obligatory to let the beard grow and leave it as is, and it is a confirmed recommended practice (sunnah) for a person to trim the mustache. For this reason, it came in a hadith: So some scholars held that trimming the mustache is obligatory, saying that leaving the trimming of the mustache is among the major sins, because the Prophet (peace and blessings be upon him) disavowed it. Among those who explicitly stated this is Ibn Hazm (may Allah have mercy on him), who said: Letting the beard grow and trimming the mustache is obligatory. Yes.