Al-Tirmidhi narrated that the freed slave of Al Zubayr said: The Messenger of Allah said:
The disease of the nations who came before you has started to spread among you: jealousy and hatred. This is the 'shaver' (destroyer); I do not say that it shaves hair, but that it shaves (destroys) faith. By the One in Whose Hand is my soul, you will not enter Paradise until you believe, and you will not believe until you love one another. Shall I not tell you of that which will strengthen love between you? Spread (the greeting of) Salaam amongst yourselves.Al-Tirmidhi, 2510
It was narrated that Abu Huraira (RA) said: The Messenger of Allah (PBUH) said:
My Ummah will be stricken with the disease of the other nations.
What is the disease of the other nations?
He (PBUH) said:
Insolence, arrogance, accumulation (of wealth), competition in worldly gains, mutual hatred and envy, until there will be wrongdoing and then killing
Al-Tabrani in Al-Awsat, Ibn Abit-Dunya)