釋禪波羅蜜次第法門 2.107

2.107

Doubt regarding oneself means that a person thinks: “My faculties are dull and obtuse, my karmic stains are deep and heavy; am I not an unfit vessel?” Entertaining this self-doubt, the dharma of concentration will never arise. If one wishes to eliminate it, one must not belittle oneself, because wholesome roots from past lives are difficult to measure.