What does the sentence "eat and sleep and beat Zheng" mean? Where is the source?

At that time, Zheng was also very poor and his geographical position was not very good. It lies between two great powers. When these two great powers fight, it will always spread to Zheng in the middle.

During the Spring and Autumn Period and the Warring States Period in ancient China, Zheng was sandwiched between two great powers, Jin and Chu, and the two great powers often fought wars, so Zheng was always implicated for no reason, and was beaten by the overlord party whenever anything happened. In fact, Zheng has been in a position of being beaten, and it is not without reason.

According to legend, when Jin Wengong couldn't escape to China, Zheng Wengong didn't greet the victim Jin Wengong, but urged him to leave quickly. Later, when he returned to the state of Jin, the recruits attacked Zheng. How can a weak Zheng win the state of Jing? At the same time, after the war, Zheng sent troops to help Chu, so he decided to lead the Jin army and destroy Zheng in one fell swoop. But the miracle is that, with his golden words, Candlewick said that he had retired the army of the State of Qin, and Zheng was able to survive, but then Zheng could only be attached to the State of Jin carefully.

However, the State of Zheng was not honestly attached to the State of Jin. After Chu Zhuangwang of Chu succeeded to the throne, the national strength of Chu became strong rapidly, and the State of Zheng in have it both ways also fell to Chu. How can such a country not be annoying? Therefore, in the future, the State of Jin will attack the State of Zheng at the first opportunity. Zheng is often attacked by several countries and has no strength to fight back. If Zheng honestly developed his country's national strength, he should not be so aggressive.