Don't do evil because it's small, don't do good because it's small. The earliest source is Pei Song's annotation in "Three Kingdoms·Book of Shu·Biography of the First Master".

Don’t do evil because it’s small, and don’t do good because it’s small. Only those who are virtuous and virtuous can obey others. Your father has a weak virtue, so don’t imitate him. You can read "Book of Han" and "Book of Rites", and read the Masters and "Six Tao" and "Book of Shang Jun" in your spare time to benefit people's mind and wisdom.

——Quoted from "Three Kingdoms, Book of Shu, Biography of the First Master, Notes"

Zhuge Liang's "Shishi Biao" is also available, and it should be quoted from Liu Bei's words.

It means don’t do bad things because they are small, and don’t do good things because they are small.

Tips: These are the words in Liu Bei’s last edict to his son Liu Chan before his death, urging him to improve his moral character and make a difference. Good things should start from small things, and if they add up, they can become big things; bad things should also be prevented from small things, otherwise, if they add up, they can also lead to big things. Therefore, don’t not do good things just because they are small, and don’t do bad things just because they are small. If a small amount of good is accumulated, it will become a great good that benefits the world, while if a small amount of evil is accumulated, it will be "enough to disrupt the country."