諸經要集 2.42

2.42

又婆沙論云。如人觀日眼不明淨。外道書論思求之時。使慧眼不。淨如人觀月眼則明淨。佛法經論思求之時。令慧眼明淨。若思求外俗如打獼猴。唯出不淨。若思求佛法如練真金。多練多淨。

Furthermore, the Vibhāṣā says: Just as when a person looks at the sun their eyes are not clear and bright, so when one contemplates and seeks non-Buddhist books and treatises, it causes the eye of wisdom not to be clear. Just as when a person looks at the moon their eyes are clear and bright, so when one contemplates and seeks Buddhist sūtras and treatises, it causes the eye of wisdom to be clear and bright. If one contemplates and seeks worldly, external texts, it is like striking a macaque—only filth comes out. If one contemplates and seeks the Buddha's Dharma, it is like refining pure gold—the more it is refined, the purer it becomes.