What is the ruling on growing a beard, and is it permissible to trim or shorten it? What is the ruling on obeying parents if they ask one to shave or trim it to secure a job and avoid security suspicions? Are there cases of necessity that permit shortening it?

Lengthening the beard is a religious obligation, which is the opinion of the majority of scholars, and there is a reported consensus on the impermissibility of shaving it. Many scholars have permitted trimming whatever exceeds a fistful of it, while Shafi'is and Hanafis disliked trimming anything less than that. As for taking from it less than a fistful, many scholars have deemed it weak. It is not permissible to shave the beard or trim from it except in cases of extreme necessity that permit forbidden things, such as not finding a job.