大毘盧遮那成佛經疏 2.87

2.87

第五十八「云何穴等心？謂先決定彼，後復變改為性」者，譬如完堅之器，後若遇緣穿穴，無所堪任。此心亦爾，初時多所受持，後稍穿漏也。或初發心受戒時具足無缺，不久漸生漏法，同於已敗之器法水不停。凡如此例，皆名穴心也。故行者常令所為之事皆有終始。又知性多變改，最能障礙堅固菩提心，為彼對治。

As for the fifty-eighth, “What is the hole-like mind? Its nature is to first decide upon that, and later alter it”: For example, an intact and solid vessel, if it subsequently encounters conditions that pierce a hole in it, is fit for nothing. This mind is also like this: at first it receives and holds much, but later it gradually leaks. Or when first generating the mind [for enlightenment] and receiving the precepts, it is complete and flawless, but before long it gradually gives rise to outflows of dharmas, identical to a ruined vessel where the water of Dharma does not stay. All such instances are called the hole-like mind. Therefore practitioners should always ensure that whatever matters they undertake have a beginning and an end. Moreover, knowing that its nature changes often and can most severely obstruct the firm bodhicitta is its antidote.