四分律刪繁補闕行事鈔 1.128

1.128

汎論僧義，並取四人已上，能御聖法，辨得前事者，名之為僧。若狂亂、睡眠、所為之人，通及能所，相有乖越，不入僧數。通而辨僧，則有七種。始從一人，乃至二十人，各有成敗不同，廣如別鈔。

Speaking generally of the meaning of saṃgha, it always takes four or more persons who can execute the holy Dharma and accomplish the matter at hand to be called a saṃgha. If one is insane, asleep, or the subject of the karman—extending to both the agent and the recipient—if their condition deviates, they are not counted in the number of the saṃgha. Comprehensively distinguishing the saṃgha, there are seven kinds. Starting from one person up to twenty persons, each has different successes and failures, as detailed in the separate commentary.