you would be among the people of the Fire—that is, because you have denied one of the pillars of faith, and whoever rejects a single pillar has, in effect, rejected them all.

Overall meaning of the report: ʿAbd Allah ibn Fīrūz ad-Dailamī narrates that a doubt arose in his mind concerning the divine decree (qadar). Fearing it might lead him to disavow that belief, he sought out the knowledgeable Companions of the Messenger of Allah to resolve the matter. Thus should every believer act, asking the scholars about whatever troubles him, in obedience to Allah’s statement: “Ask the people of knowledge if you do not know” (Surah al-Naḥl, 43). All of those scholars gave him the same verdict: faith in Allah’s decision and predestination is indispensable, and whoever dies without that belief will be one of the people of the Fire.

Why this narration is cited in the chapter: to clarify that belief in the decree is obligatory, and that this ruling is what the Companions conveyed from their Prophet ﷺ.

Points derived from the narration:
1- A stern warning is issued against anyone who does not believe in the divine decree.
2- The duty to consult scholars about problematic matters of creed and elsewhere.
3- One of the scholars’ functions is to dispel doubts and spread knowledge among the people.