Repaying a grievance with a straight line
The synonym "complaint by direct" generally refers to "complaint by direct". As a Chinese idiom, Pinyin is y à zh í B à oyu à n, which means to treat the person who resents fairly. It comes from the Analects of Confucius.
The origin of Idioms
In the Analects of Confucius, Xian Wen: "to repay resentment with uprightness, to repay virtue with virtue."
Idiom usage
It refers to the attitude towards people. example it's called repaying one's grievance with one's uprightness and repaying one's virtue with one's virtue. Feng Menglong's a warning to the world in Ming Dynasty (Volume 11)
justice in return for injustice
racing together bridle to bridle - bìng jià qí qū
stamp one 's feet and beat one 's breast - dùn zú chuí xiōng
fly swiftly as a frightened swan goose - piān ruò jīng hóng
wear a funeral face as if newly bereft of both parents - ruò sàng kǎo bǐ