Maliks Muwatta Book 47, Hadith Number 14.

Section : Shunning People.

Yahya related to me from Malik from Ibn Shihab from Anas ibn Malik that the Messenger of Allah, may Allah bless him and grant him peace, said, “Do not be angry with each other and do not envy each other and do not turn away from each other, and be slaves of Allah, brothers. It is not halal for a muslim to shun his brother for more than three nights.”