Leave something unfinished
半途而废
bàntú'érfèi

It literally means "give up halfway".

The Story:
This story is about a man named Yue Yangzi, he learns two valuable lessons in his life and both lessons came from the support of his wife. The first was to never bring things home (gold) found on the street because they are not originally yours and it is shameful to considered it as your own. "Its said that a man of ambition neither drinks a thief's water nor accepts insulting handouts. The second lesson was after Yue Yangzi went away to study, he came back early because he missed his wife. His wife took him aside and said, "Day and night, and one thread after another, I manage to weave inches and meters long brocades. Now if i cut them in the middle, all my previous efforts would be wasted. It's the same as your studying. If you give up halfway, isn't it just like cutting in the middle instead of at the end"? So after this he went back and completed his studies for seven years.