大乘起信論義記 1.138

1.138

○乘中二：「一切諸佛本所乘故。」先標果望因以解乘。「一切菩薩皆乘此法到如來地故。」後舉因望果以成運。即始覺之智是能乘，本覺之理為所乘，故《攝論》云「乘大性故，名為大乘。」立義分竟。

In [the explanation of] "vehicle" there are two: "Because it is that which all Buddhas originally rode upon." First, it presents the fruit looking back to the cause to explain "vehicle." "Because all bodhisattvas ride upon this Dharma to reach the ground of the Tathāgata." Second, it brings forth the cause looking toward the fruit to establish conveyance. That is, the cognition of incipient enlightenment is that which can ride; the principle of innate enlightenment is that which is ridden. Hence the Mahāyānasaṃgraha says: "Because it rides upon the great nature, it is called the Great Vehicle." The Section on Establishing the Meaning is finished.