Imran bin Abi Anas عمران بن أبي أنس القرشي العامري · General Behavior (Kitab Al-Adab)

The Messenger of Allah (ﷺ) said: It is not right for a Muslim to keep apart from another Muslim for more than three days. Then when he meets him and gives three salutations, receiving during that time no response, the other bears his sin.