It is narrated from Hazrat Abu Ayyub Ansari (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: It is not permissible for a Muslim to sever relations with his brother for more than three days; when they meet, one turns his face this way and the other that way, and the better of the two is the one who initiates the greeting of peace (salaam).
Hadith Referenceمسند احمد / مسند الأنصار رضي الله عنهم / 23528