Answer:
“Ibn Umar (Radiyallaahu Anhu) narrates that the Messenger (sallallaahu alaihi wa sallam) said, “Do the opposite of what the mushrikeen (polytheists) do. Let the beard grow and trim the moustache.”
The hadith above appears in many books of hadith with slight variation in the words. From such ahaadith, the jurists have deduced that letting the beard grow is compulsory, as in these ahaadith the Prophet (sallallahu alaihi wa sallam) commanded us to let our beard grow.
However, because of narrations in which it is mentioned that some sahabah would hold their beard with their fist and trim any excess, the jurists have deemed it permissible to trim one’s beard by holding it with one’s fist and trimming any hair from the beard that extends beyond the fist. For instance, it is mentioned in Sahih Bukhari, after the aforementioned hadith, that whenever Ibn Umar (Radiyallahu Anhu) would do Hajj or Umrah, he would hold his beard with his fist and trim any excess.
However, note that trimming one’s beard shorter than a fist in size is not permissible and is a great sin.
Mufti Faizal Riza
4/10/2011