Is it Sunnah, Wajib or Fard to grow beard in Islam?
Darhi ka Wujjob is an e book authored by Molna Zikriya Kandhalvi r.a. that consist of concepts of beard in Islam.
Allah says in the Holy Quran Chapter 33 Surah Ahzab verse 21:
There is indeed the best model for you in the Messenger of Allah, for every such person looks forward to Allah and the Last Day, and remember Allah much.
Ibn 'Umar related that the Messenger of Allah (saws) said: "Differ from the polytheists: let your beards (grow), and trim your moustache."
Related by al-Bukhari and Muslim.