大乘百法明門論開宗義決 1.46

1.46

剋用理智而為體者。以是能證所證法故。攝有無為一切功德故。一切功德之依處故。故與理智正為乘體。而於教果兼名乘者。以教顯理。得理云教。智即是行。有行成果。是故教果兼名大乘。

Regarding "specifically taking principle and wisdom as its substance": Because they are the dharmas that realize and are realized; because they gather all conditioned and unconditioned virtues; and because they are the foundation of all virtues; therefore, principle and wisdom are properly the substance of the vehicle. As for the teaching and the fruit being concurrently called the vehicle: teaching reveals principle, and realizing principle is called teaching; wisdom is practice, and having practice results in the fruit; therefore, teaching and fruit are concurrently called Mahāyāna.