佛遺教經論疏節要 1.297

1.297

以成就不退轉故，勸修習長養。由精進匪間，如水不絕則穿石也。二懈怠況火數息。

In order to achieve non-retrogression, one is exhorted to cultivate and nurture it. Because diligence is uninterrupted, just as water that does not cease bores through stone. Second, likening indolence to fire frequently interrupted.