大乘入道次第開決 1.85

1.85

願者所習等者。願是菩薩本所修行。故十度中而有願度。誓即是願讚助之緣。以誓助願願方成故。或由願樂方能修行。故願即是行之本矣。後以誓助行得增長。故誓於行為助緣矣。

Regarding “vows are what is practiced,” and so forth: vows are what a bodhisattva originally practices; therefore, among the ten pāramitās there is the vow pāramitā. A pledge (samaya) is a supporting condition that assists the vow, because only when the pledge assists the vow is the vow fulfilled. Or, it is due to aspiration that one is able to practice, and thus the vow is the root of practice. Later, with the pledge assisting, practice increases and grows, so the pledge is a supporting condition for practice.