Sahih Al Bukhari – Book of Good Manners And Form (Al-Adab)
Volumn 008, Book 073, Hadith Number 091.
—————————————–
Narated By Anas bin Malik : Allah's Apostle PBUH 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."