Sahih Bukhari Volume 008, Book 073, Hadith Number 091.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 73. Good Manners and Form (Al-Adab)
Narated By Anas bin Malik : Allah's Apostle said, "Do not hate one another, and do not be jealous of one another, and do not desert each other, and O, Allah's worshipers! Be brothers. Lo! It is not permissible for any Muslim to desert (not talk to) his brother (Muslim) for more than three days."