sn.45.140 Saṁyutta Nikāya (Linked Discourses)

“Bhikkhus, just as the footprints of all living beings that walk fit into the footprint of the elephant, and the elephant’s footprint is declared to be the chief among them, that is, with respect to size, so too whatever wholesome states there are, they are all rooted in diligence, converge upon diligence, and diligence is declared to be the chief among them. When a bhikkhu is diligent, it is to be expected that he will develop and cultivate the Noble Eightfold Path….”