俱舍論頌疏論本 18.24

18.24

釋曰：贍部洲者，唯贍部洲能破法輪，以有佛故。九等者，要須九人，謂八苾芻分為二眾以為所破，四為正眾、四是邪眾。能破第九，故眾極少由須九人。等言，為明多亦無限。

Explanation: "In Jambudvīpa": only in Jambudvīpa can the wheel of the Dharma be split, because there is a Buddha there. "Nine or more": there must be nine persons; that is, eight monks divided into two assemblies to be what is split—four being the orthodox assembly and four being the heterodox assembly. The one capable of splitting is the ninth; hence the assembly at its minimum must consist of nine persons. The word "or more" is to clarify that there is no upper limit to having more.