Letting the beard grow is a command of the Prophet ﷺ and part of the fiṭrah. He ﷺ said: “Trim the moustaches and let the beard grow; differ from the polytheists.” (al-Bukhārī & Muslim). It is a visible mark of following him ﷺ.
العربية: عن ابن عمر رضي الله عنهما أنّ رسول الله ﷺ قال: «خالِفوا المشركين، أحفُوا الشوارب، وأوفُوا اللِّحى». (البخاري ومسلم).
For men: keep the beard and trim the moustache — a Sunnah of the Prophet ﷺ and of the prophets before him.