佛垂般涅槃略說教誡經 1.12

1.12

「汝等比丘，若勤精進則事無難者，是故汝等當勤精進，譬如小水常流則能穿石。若行者之心數數懈廢，譬如鑽火未熱而息，雖欲得火，火難可得。是名精進。

“You monks, if you are diligent and energetic, nothing is difficult. Therefore, you should be diligent and energetic, just as a small stream of water flowing constantly can pierce stone. If a practitioner's mind frequently becomes lax and slack, it is like rubbing sticks for fire and stopping before they grow hot; though one wants to get fire, fire is hard to obtain. This is called vigor.