It is narrated from Sayyiduna Sa’d (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: “Fighting with a Muslim is disbelief, and abusing him is wickedness, and it is not permissible for any Muslim to cut off relations with his brother for more than three days.”
Hadith Referenceمسند احمد / مسند باقي العشرة المبشرين بالجنة / 1519
Hadith Gradingحکم دارالسلام:إسناده حسن، والحديث صحيح .