楞伽阿跋多羅寶經註解 4.84

4.84

此喻如來立教之意。若論出世本意，惟說一乘以度群生，如大醫王但以阿伽陀藥遍治眾病，故云「無有若千論。」然機器不齊，未免曲垂方便，為說三乘，漸次調伏，如隨病差別設種種藥。然非根異而法有殊，權機若熟，咸歸一實，所謂十方佛土中，唯有一乘法也。

This illustrates the Tathāgata's intention in establishing the teachings. If one considers the original intent of his appearing in the world, it is solely to teach the One Vehicle to deliver all beings, just as a great king of physicians uses only the agada medicine to cure all diseases comprehensively; hence it is said: "Has no diverse theories." However, because their capacities are not uniform, he cannot but accommodate them with expedients, teaching the three vehicles for them and gradually taming them, just as various medicines are set forth according to differences in diseases. Yet it is not that because faculties differ, dharmas are genuinely distinct; when provisional capacities ripen, all return to the one real [vehicle]—what is termed: "In the Buddha lands of the ten directions, there is only the one-vehicle Dharma."