Sunan Abi Dawud 4911
سنن أبي داود#4911SahihAbu Ayyub al-Ansari reported the Messenger of Allah (May peace be upon him) as saying :it is not allowable for a Muslim to keep apart from his brother for more than three days. When they meet, this turns away from him, and that turns away from him. The better of the two is the one who initiates in salutation
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Shuaib Al ArnautSahih
Zubair Ali ZaiSahih Bukhari (6077) Sahih Muslim (2560)
In-book reference: 43:139