法華義疏 4.104

4.104

今文現通開發正說之由漸故名方便，前明說法門以無三說三故名方便。

In the present text, manifesting supernatural powers opens and initiates the gradual approach to the correct preaching, hence it is called an expedient means; the previous gate of preaching the Dharma is called an expedient means because, where there were no three, he preached the three.