首楞嚴義疏注經 6.214

6.214

跋陀婆羅忽悟水因，既不洗塵，亦不洗體，中間安然得無所有，妙觸宣明，由是證果。今明此觸因所觸身而得顯發，無所不顯，性非常定，故不圓通。

Bhadrapāla suddenly awakened to the cause of water: washing neither dirt nor body, peacefully finding nothing in between, wonderful touch was clearly proclaimed, and from this he realized the fruit. Now it is explained that this touch becomes manifest through the body that is touched; where there is no manifestation, its nature is not constantly fixed; therefore it is not perfect penetration.