Source 1
"The Analects of Confucius·Xianwen": "Don't complain about heaven, don't blame others, learn from the bottom and reach the top, the one who knows me is the heaven!"
Origin 2
When you are in a superior position, you do not care about others; when you are in a inferior position, you do not support your superiors; when you are in a position of superiority, you do not ask for help from others. The superior does not complain about heaven, and the inferior does not blame others. Therefore, a gentleman lives in Yi to wait for his fate, and a villain takes risks to get lucky.
--"The Doctrine of the Mean. Chapter Fourteen"