摩訶止觀 4.36

4.36

復次，觀心持戒，即是「五名」。所以者何？「防止」是戒義，觀亦如是。三觀名能防，三惑名所防。如此防止，義遍法界，不局在身口（云云）。

Furthermore, contemplating the mind to uphold the precepts is identical to the "five designations." Why is this? "Warding off and stopping" is the meaning of precept, and contemplation is also like this. The three contemplations are named that which can ward off; the three delusions are named that which is warded off. Such warding off and stopping pervades the dharmadhātu in meaning, not restricted to body and speech (and so forth).