From Sahih Bukhari (Hadith 6065):
Narrated Anas bin Malik:Allah's Messenger (ﷺ) 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
Reference: Bukhari 6065