Nakhasikha sutta: A Fingernail

At Sāvatthī.

Then the Buddha, picking up a little bit of dirt on his fingernail, addressed the mendicants: “What do you think, mendicants? Which is more: the little bit of dirt on my fingernail, or this great earth?”

“Sir, the great earth is far more. The little bit of dirt on your fingernail is tiny. Compared to the great earth, it doesn’t count, there’s no comparison, it’s not worth a fraction.”

“In the same way the sentient beings reborn as humans are few, while those not reborn as humans are many.

So you should train like this: ‘We will stay diligent.’ That’s how you should train.”