四分律刪繁補闕行事鈔 1.130

1.130

二、五人僧者。謂邊地受戒、自恣等法。若據《僧祇》，捨墮懺悔，五人僧攝；謂受懺悔主，作白和僧，為他所量，不入僧數。今以當宗不了，《僧祇》為定。

Second, the five-person saṃgha: this is for rituals such as ordination in borderlands and pravāraṇā. According to the Mahāsāṃghika, confession of an offense of relinquishment and expiation (nihsargika-pāyattika) is subsumed under a five-person saṃgha; that is, the master who receives the confession, who makes the announcement to harmonize the saṃgha, is being assessed for the other person and is not counted in the number of the saṃgha. Now, because our own school is not clear on this, the Mahāsāṃghika is taken as definitive.