The Messenger of Allah ﷺ said, "It is not permissible for a Muslim to shun his brother for more than three days."
قال رسول الله ﷺ: لا يحل لمسلم أن يهجر أخاه فوق ثلاث.
Ahmad (1589), Bazzar in Kashf Astar (2051), and Abu Yaala (720) all narrated it via the route of Israil, from Abu Ishaq, from Muhammad bin Saad bin Malik, from his father, who mentioned it. Its chain of transmission is sahih.