大毘盧遮那經供養次第法疏 2.28

2.28

This meaning speaks of the great power of all Buddhas. What kind of power is this great power? It is the Tathāgata's ten powers, which are the greatest among all powers. How did the Tathāgata obtain these ten powers? They were obtained from great compassion; hence it is said that this power arises from great compassion. Fourth, from "Next, by using..." onwards up to "are all able to protect universally," is the mantra gate of binding the great boundary. Next is the mantra for binding the great boundary. As the Buddha said, there are further immeasurable vidyādharas; fearing that other vidyādhara mantrins and the like, without boundary-protection having been bound, would disrupt the ritual actions and harm the reciter, the method of binding the boundary was established. Because of binding the boundary, even various vidyādharas cannot destroy it. Just as when bhikṣus bind a boundary to perform ritual acts, a bhikṣu outside the boundary, even if performing rites, cannot obstruct or disrupt them.