肇論新疏 3.261

3.261

而難云：三乘之道皆因無為而有差別。此以人三，三於無為，非無為有三也。

Yet the objection states: "The paths of the three vehicles all have distinctions because of the unconditioned." This means that the persons are three and are differentiated with respect to the unconditioned; it does not mean that the unconditioned itself has three [types].