大乘起信論略述 1.116

1.116

論。三者執取相至心起著故　述曰。於前所取苦樂等境不了虛無。深起取著。名執取相。謂即於前相續所念苦樂境上復深執著住持不捨。故言心起著等。

The treatise says: "Third is the aspect of attachment, [...] the mind conceives clinging."

The commentary says: Toward the previously apprehended objects of suffering, pleasure, and so forth, one fails to understand their unreality and deeply gives rise to grasping and attachment; this is named the aspect of attachment. That is to say, toward the objects of suffering and pleasure contemplated in the preceding continuity, one further deeply clings to them, holding fast and not letting go; hence it says "the mind conceives clinging," and so forth.