大毘盧遮那成佛經疏 10.135

10.135

然此真言以此帝㘑字為體，上有多聲即是如如之義。囉是垢障。有伊聲即是三昧，以如如之體即是本來不生。以不生故，即垢障亦自本來不生。稱此理而修定慧俱足，故能降伏三世也。

Now, this mantra takes this syllable tri as its substance; above it has the ta sound, which means tathatā. Ra is defilement-obstruction. It has the i sound, which is samādhi; for the substance of tathatā is originally unborn. Because it is unborn, defilements and obstructions are also originally unborn of themselves. Cultivating in accord with this principle, one is fully endowed with both concentration and wisdom, and is thus able to subjugate the three worlds.