It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that I heard the Prophet (peace and blessings of Allah be upon him) say: "It is not permissible for a man to forsake his believing brother for more than three days. When three days have passed, he should meet him and greet him with salam. If he returns the salam, then both share in the reward, and if he does not reply, then the one who offered salam is absolved of the sin of severing ties."
Hadith Referenceالادب المفرد / كتاب / 414
Hadith Gradingالألبانی:ضعيف
Hadith Takhrij«ضعيف : أخرجه أبوداؤد ، كتاب الأدب ، باب فيمن يهجر أخاه المسلم : 4912 - الإرواء : 94/7»