Sahih Muslim Book 32, Hadith Number 6205.

Chapter : Forbiddance of nursing mutual jealousy mutual hatred and mutual hostility.

Anas b. Malik reported Allah’s Messenger (may peace be upon him) as saying: Neither nurse mutual hatred, nor jealousy, nor enmity, and become as fellow brothers and servants of Allah. It is not lawful for a Muslim that he should keep his relations estranged with his brother beyond three days.