大毘盧遮那成佛經疏 13.13

13.13

爾時世尊住於無害身力三昧者，佛為滿斯願故，復入三昧。此即是如來無量之身自在之力，故無能害也。住此三昧而發三明真言，其明名為無礙無害無等力也。由此三昧耶，諸學者得聽聞、得入正法。若不作者，即不合入壇，亦不合聽祕教也。若修此明，即能得身淨語淨，所願滿足會於三身，故名為三明也。三力者，謂三世力或是三平等力也。無等力者，即此三力也。其明次當說之耳。

"At that time, the World-Honoured One dwelt in the samādhi of the unassailable bodily power": in order to fulfill this wish, the Buddha again entered samādhi. This is the sovereign power of the Tathāgata's immeasurable body, and therefore none can harm it. Dwelling in this samādhi, he uttered the three-vidyā mantra; its vidyā is named unhindered, unassailable, and unequalled power. By virtue of this samaya, all learners are able to hear and enter the true Dharma. If one does not perform it, one is not qualified to enter the altar, nor qualified to hear the secret teaching. If one cultivates this vidyā, one can attain purity of body and purity of speech, have one's wishes fulfilled, and unite with the three bodies; hence it is called the three vidyās. The three powers refer to the power of the three times or the power of the three equalities. The unequalled power is these very three powers. Its vidyā will be explained next.