Abu Hurairah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings of Allah be upon him) said: "It is not permissible for a believer to shun another believer for more than three days. When three days have passed, he should meet him and greet him with salam. If the other responds to the salam, then both share in the reward; but if he does not respond, then that person bears the sin, while the one who offered salam is absolved from the act of shunning." Its chain is weak. Narrated by Abu Dawood.