Maybe it is worth pointing at the fact that this hadith includes two parts:
A part which we can regard as a hadith or a report of a statement from the prophet():
“The Hour will be established while the Romans are the majority of people.”
A part which is a report of the interpretation or comment of a sahabi() -'Amr ibn al-'Aas- on the above statement of ...
First of all the hadith in Sahih Muslim has two parts:
I heard Allah's Messenger (ﷺ) as saying: When any one of you stays at a place, he should say:" I seek refuge in the Perfect Word of Allah from the evil of that He created." Nothing would then do him any harm until he moves from that place.
which was reported on the authority of Khawla bint ...