首楞嚴義疏注經 1.263

1.263

具云兜沙羅，此云霜，佛手柔軟如兜羅綿，三十二相中一相也。眼屬身分，心若離者合不分別，若分別者應不離身，以不離故名為相知。故此責云若相知者云何在外。

In full it is called tuṣāra, which is translated here as frost; the Buddha's hands are soft like tūla-cotton, one of the thirty-two marks. The eyes belong to the body's part; if the mind were apart from it, it should not discriminate, and if it discriminates, it should not be apart from the body; because they are not apart, it is called mutual knowing. Therefore, this rebukes him, saying: if they mutually know, how could it be outside?