´'Abdullah bin Mas'ud narrated that the Messenger of Allah said:` "Verbally abusing the Muslim is disobedience and fighting him is disbelief." Zubaid said:"I said to Abu Wa'il: 'Did you hear it from 'Abdullah?' He said: 'Yes.'"
Hadith Referenceسنن ترمذي / كتاب البر والصلة عن رسول الله صلى الله عليه وسلم / 1983