法華義疏 8.183

8.183

本有三乘根性故說三車；二乘人領解，知唯此一事實餘二則非真，故稱二使；二乘雖異，同斷見思煩惱、同得無為涅槃，故名一城也。

Because there were originally triyāna dispositions, the three carriages were spoken of; the persons of the two vehicles grasped and understood, knowing that only this one matter is real while the other two are not true, and hence they are called the two emissaries; although the two vehicles differ, they equally sever the afflictions of views and thoughts and equally attain unconditioned nirvāṇa, and hence it is called one city.