`Abdullah b. `Amr b. al-`As reported that Allah's Messenger (ﷺ) said:
How would you be, O people, when Persia and Rome would be conquered for you? `Abd ar-Rahman b `Auf said: We would say as Allah has commanded us and we would express our gratitude to Allah. Thereupon Allah's Messenger (ﷺ) said: Nothing else besides it? You would (in fact) vie with one another, then you would feel jealous, then your relations would be estranged and then you will bear enmity against one another, or something to the same effect. Then you would go to the poor emigrants and would make some the masters of the others.
Reference: Sahih Muslim 2962
In-book reference: Book 55, Hadith 11
USC-MSA web (English) reference(deprecated numbering scheme): Book 42, Hadith 7067