2:259 How Was This Made As A Sign?
Vision here means mushahidaad, not a roiya (dream).
This primary purpose of this incident has been served completely i.e. ‘response of seekers of truth / believers in comparison to people who have decided not to accept the truth despite its clarity and how God treats each one of them differently based on their attitude towards the truth’. But if you want to narrow down on the smallest of the details like what does this ‘making of sign’ means and for whom etc. then you have to consult other scriptures to explore it further. But primarily, the objective was met in entirety without any recourse to previous divine scriptures.