Know that associating with people in the manner mentioned above was the practice adopted by the Prophet (may Allah’s peace and blessings be upon him), all the prophets (peace be upon them), the rightly-guided Caliphs, the Companions and the succeeding generation, and after them the scholars and the righteous among the Muslims. This was also the opinion held by Al-Shāfi‘i, Ahmad, and most other scholars (may Allah be pleased with them all). Allah Almighty says: {And cooperate in righteousness and piety} [Al-Mā’idah: 2] The verses indicating this meaning are many and well known.
The explanation favored by Al-Nawawi (may Allah have mercy upon him) is the one supported by this Hadīth: “There will come a time when the best among people will be a man who holds the reins of his horse (ever ready to march) in the way of Allah. Whenever he hears the war cry, he settles on its back then he seeks death at places where it is expected. And a man who lives in one of these mountain passes, where he prays, pays the obligatory alms, and keeps away from people except in what is good.” [Narrated by Ahmad]
And the Hadīth: “A believer who associates with people and patiently endures their harm is better than a believer who does not associate with people and does not patiently endure their harm.” [Narrated by Ahmad]
Guidance from the verse: {And cooperate in righteousness and piety}
1) The believers cooperate in righteousness and piety, and this is their slogan when they get together.
2) People’s interests necessitate that they hold gatherings, because it is by gathering that benefits can be realized.