Sunan Abi Dawud 4910
سنن أبي داود#4910SahihAnas b. Malik reported the Messenger of Allah (May peace be upon him) as saying:Do not hate each other; do not envy each other; do not desert each other; and be the servants of Allah as brethren. It is not allowed for a Muslim to keep apart from his brother for more than three days
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 (6075) Sahih Muslim (2559)
In-book reference: 43:138