What is the ruling on growing a beard and shortening one's garment, and is there a sin upon one who does not do so in light of the fear of harm and the existence of a statement by one of the shaykhs that Ibn Hazm forbade his son from shortening his garment?

It is obligatory to grow a beard and forbidden to shave it. However, it is permissible to shave or trim it if doing so prevents a definite harm that cannot be averted otherwise. Most scholars are of the view that the prohibition of isbal (letting one's garment hang below the ankles) is restricted to arrogance, and the prohibition ceases when arrogance is absent. It is permissible to practice isbal to the extent that it prevents a definite harm that is difficult to endure.