Mukhtasar Bukhari

Narrated from Sayyiduna Abu Ayyub Ansari (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) said: "It is not permissible for a Muslim to abandon meeting his (Muslim) brother for more than three nights (i.e.), when they meet, one turns his face away from the other and the other turns his face away from him, and the better of the two is the one who initiates the greeting and meeting."