Is the recitation of Surat Al-Mulk before sleep obligatory in order to avoid punishment for one who commands something he does not do?

"A sermon concerning what is feared is easy, and its consequences are light; because it falls within the sphere of commendable virtues. The matter becomes more serious if it falls within the sphere of obligatory duties. A servant is required to do good and enjoin it, and refraining from the act does not negate the obligation to enjoin."