The beard is a wajib in fiqh terminology, that means that it’s obligatory and the one who shaves it has done a sin.
Here we’ll bring some ahadith for that claiming:
Narrated Ibn `Umar:
Allah’s Messenger (ﷺ) said, “Cut the moustaches short and leave the beard (as it is).
The most ahadith are narrated from Ibn ‘Umar with different chains
Abu Huraira reported:The Messenger of Allah (ﷺ) said: Trim closely the moustache, and grow beard, and thus act against the fire-worshippers.
The ‘ulama understood that theese ahadith are an commandmant.
Shaving the beard is immitating the kuffar, the women and changing the creation of Allah s.w.t.
Immitating the kuffar:
Ibn Umar said:The Messenger of Allah (may peace be opon him) said: Act against the polytheists, trim closely the moustache and grow beard.
Shaykh Al Albani said: “The one who allows immitating the kuffar especially shaving the beard does a big mistake, bacause it’s a external immitation that’s very similiar to the inner (heart).
This means anyone who immitates the kuffar, means he allowes the disbelief of them, and in the same time doesn’t accept the guidance of the Messenger s.a.w.s.
Immitating the women:
Narrated Ibn `Abbas:
Allah’s Messenger (ﷺ) cursed those men who are in the similitude (assume the manners) of women and those women who are in the similitude (assume the manners) of men.
Changing the creation of Allah s.w.t:
119. Verily, I will mislead them, and surely, I will arouse in them false desires; and certainly, I will order them to slit the ears of cattle, and indeed I will order them to change the nature created by Allah.” And whoever takes Shaitan (Satan) as a Wali (protector or helper) instead of Allah, has surely suffered a manifest loss. Surah4