Do you know of a Buddhist text explaining why living in a community?

There are a number of texts explaining **how** to live in a community, what rules to follow, what activities, etc. For instance, the classical Vinaya texts, or the "Standards and Rules of Purity" genre in China and Japan (ex.: Chanyuan qinggui, Dogen's Ehei Shingi, etc). However, I am looking for traditional texts that explain **why** to live in a community. It could be aimed at monks, lay people, or both. The denomination does not matter much. I'm looking for commentaries or treatises rather than sutras. It is to use the material as a basis for giving lectures.