Fiqh-us-Sunnah Volume 1, Purification and Prayer, Fiqh 1.022.
Section : Letting one’s beard grow and become thick.
This is a feature of dignity. It should not be cut so short that it appears like a shaved beard, nor should it be left so long that it becomes untidy. It is also a sign of manhood. Says al-Bukhari, “Whenever Ibn ‘Umar made the hajj or ‘umrah, he would hold his beard in his fist and, whatever exceeded his fist, he would cut off.”