Kitāb al-Muʾmin
Hadith 9898 - وعن أبي عبد الله (ع) قال: قال النبي (ص) المُسلمُ أخو المسلمِ لا يخونُه ولا يخذِلُه ولا يعيبُه ولا يحرمُه ولا يغتابُه.
98. It has been reported that Abu 'Abd Allah (a.s) said: The Prophet (a.s) said: A Muslim is a brother to the other Muslim; he must not betray him, desert him, disgrace him, excommunicate him nor backbite him.