Yahya related to me from Malik from Ibn Shihab from Ata ibn Yazid al-Laythi from Abu Ayyub al-Ansari that the Messenger of Allah, may Allah bless him and grant him peace, said, "It is not halal for a muslim to shun his brother for more than three nights, that is they meet, and this one turns away and that one turns away. The better of the two is the one who says the greeting first

English translation · Muwatta Malik