Wa `alaykum As-Salamu wa Rahmatullahi wa Barakatuh

 

Scholars have different views on the actual growing of the beard itself. Many scholars consider it an obligation and that the length of it must be that which your hand can grab or bigger.

 

Few consider it a human act by the Prophet (peace be upon him) with no religious reference at all so even if shaved it should be fine.

 

Others consider it a Sunnah to grow even a little bit to cover your cheek regardless of the length and that it is Makrooh to cut not Haram.

 

On the trimming part particularly, all scholars approve to remove extra hair that is growing outside the norm and to keep it looking good and clean.

 

Almighty Allah knows best.