عن عبد الله بن عمرو أن النبي صلى الله عليه و سلم قال : بلغوا عني ولو آية ( صحيح البخاري #3274 )

Hazrat ‘Abdullah bin ‘Amr (radhiyallahu ‘anhuma) narrates that Rasulullah (sallallahu ‘alaihi wasallam) said, “Convey (the knowledge of deen) from me, even if it be just a single verse.”

The knowledge of Deen which a person acquires is, in reality, an amaanah (a trust). It is thus our responsibility to practice on this knowledge and to also propagate it to others.

As far as the fundamentals of Deen and those issues of halaal and haraam are concerned which are clear to one and all, then after acquiring the correct understanding of them, each and every Muslim should pass them on to others.

However, as far as technical aspects of Deen are concerned, they require an in depth study of Deen and its various sciences in order to be able to correctly comprehend them and are thus generally understood by highly qualified ‘Ulamaa. These intricate sciences and complex masaa’il which are not completely and adequately understood by the ordinary layman should therefore be left for the ‘Ulamaa to explain to the public.