From Sahih Muslim (Hadith 7279):
Mustaurid al-Qurashi reported:I heard Allah's Messenger (ﷺ) as saying: The Last Hour would come (when) the Romans would form a majority amongst people. 'Amr said to him (Mustaurid Qurashi): See what you are saying? He said: I say what I heard from Allah's Messenger (ﷺ). Thereupon he said: If you say that, it is a fact for they have four qualities. They have the patience to undergo a trial and immediately restore themselves to sanity after trouble and attack again after flight. They (have the quality) of being good to the destitute and the orphans, to the weak and, fifthly, the good quality in them is that they put resistance against the oppression of kings
Reference: Muslim 7279