The Messenger of Allah ﷺ said, "Fighting a Muslim is disbelief, and insulting him is wickedness. It is not lawful for a Muslim to shun his brother for more than three days."
أن رسول الله ﷺ قال: قتال المسلم كفر، وسبابه فسوق، ولا يحل لمسلم أن يهجر أخاه فوق ثلاثة أيام.
Narrated by Nasai (4104) and Ahmad (1519), both from the hadith of Abdul-Razzaq, and it is in his Musannaf (20224), he said, Mamar informed us, from Abu Ishaq, from Umar bin Saad, who said, Saad bin Abu Waqqas narrated to us, and he mentioned it.Its isnad is hasan on account of Umar bin Saad, for his hadith is hasan.