From the Dhammapada

Hold not a sin of little worth, thinking "This is little to me."
The falling drops of water will in time fill a water-jar.
Even so the foolish man becomes full of evil, although he gather it little by little.

Hold not a deed of little worth, thinking "This is little to me."
The falling drops of water will in time fill a water-jar.
Even so the wise man becomes full of good, although he gather it little by little.