Q: An inquirer from the Kingdom of Morocco asks: Is letting the beard grow a necessary characteristic that should be observed by a Muslim?
A: It is obligatory upon a Muslim to let the beard grow without shaving it, as a way of obeying the commandment of the master of the earlier and the later people, Prophet Muhammad ibn `Abdullah, the Messenger of the Lord of the Worlds. May Allah's Peace and Blessings be upon him!
This is because He (peace be upon him) said: Trim closely the mustache and let the beard grow! Be distinguished from the unbelievers! (Agreed upon by Imams AlBukhari and Muslim). This Hadith was narrated on the authority of Ibn `Umar (may Allah be pleased with them both).
Moreover, he (peace be upon him) said: Trim closely the mustache and grow the beard! Act against The Magi! Narrated by Muslim in his Sahih from the Hadith of Abu Hurayrah (may Allah be pleased with him)
It is well known that one can only attain all good in this life and in the Hereafter through obeying and following the Messenger of Allah (peace be upon him) and that all evil lies in disobeying Allah and His Messenger and following desires and Shaytan (Satan).
Say (O Muhammad ﺻﻠﻰ ﺍﷲ ﻋﻠﻴﻪ ﻭﺳﻠﻢ to mankind): "If you (really) love Allâh then follow me (i.e. accept Islâmic Monotheism, follow the Qur'ân and the Sunnah), Allâh will love you and forgive you your sins.
Then for him who transgressed all bounds, (in disbelief, oppression and evil deeds of disobedience to Allâh). And preferred the life of this world (by following his evil desires and lusts), Verily, his abode will be Hellfire; But as for him who feared standing before his Lord, and restrained himself from impure evil desires and lusts. Verily, Paradise will be his abode.
Allah (may He be Praised) condemned the polytheists for following their assumptions and desires. Thus, Allah (Glorified and Exalted be He) says in Surat AlNajm: They follow but a guess and that which they themselves desire, whereas there has surely come to them the Guidance from their Lord!
The Prophet (peace be upon him) said: My entire Ummah will enter Paradise except who refuses, then it was said: O' Messenger of Allah, who will refuse? He said, "Whoever obeys me will enter Paradise, and whoever disobeys me is the one who refuses." (Narrated by AlBukhari in his book of Sahih Hadiths)
There are many Ayahs and Hadiths on the command of obeying Allah and His Messenger and forbidding disobeying Allah and His Messenger (peace be upon him).
May Allah guide all Muslims to obey their Lord, worship Him Alone, and be devoted to Him and follow His Messenger Muhammad (peace be upon him) and hold fast to what the Prophet brought, He is AllHearer, Ever Near.