«هو فرض في حق العمل به، حتى لا يجوز تركه، ونفل في حق الاعتقاد، فلا يلزمنا الاعتقاد به، فجحوده بتأويل ليس بكفر»
Wajib is treated like fard in requiring performance, so its omission is impermissible; but it does not have the same conclusive doctrinal status as fard, and its denial through interpretation is not classified as disbelief.
The phrase “like nafl in respect of belief” is a technical contrast in this passage. It emphatically does not make a wajib optional like a voluntary prayer.
Fard and wajib resemble one another in practical obligation; they differ in the conclusiveness of evidence and related doctrinal consequences.