During the Tang Dynasty, a man named Zhang Guangsheng initially served as a cavalryman. During the An Lushan Rebellion, the famous general Geshu Han was defeated at Tong Pass, and his subordinate Wang Sili had his horse killed by a stray arrow while breaking through the encirclement. Seeing Wang Sili in danger, Zhang Guangsheng gave him his own horse, allowing Wang to escape safely.
Later, Wang Sili was appointed as the military governor of Hedong. Grateful for past kindness, he found Zhang Guangsheng, became sworn brothers with him, and promoted him to "Commander of Troops." He then petitioned the court to appoint him as "Deputy Minister of the Imperial Ancestral Temple." Thus, Zhang Guangsheng's official career soared, and his rank grew ever higher.
In 783 AD, during Emperor Dezong's reign of the Tang Dynasty, the Grand Commandant Zhu Ci exploited a mutiny to declare himself emperor, establishing the "Great Qin" dynasty. He appointed Zhang Guangsheng as his deputy general and personally led troops to attack Fengtian. However, the campaign faltered; after over a month without victory and with imperial reinforcements arriving, Zhu Ci was forced to retreat under cover of night, bringing Zhang Guangsheng back to Chang'an.
The following year, Zhu Ci again changed his dynasty's name to Han, proclaimed himself Emperor Han Yuan Tian, and appointed Zhang Guangsheng as his chancellor.
By this time, the Tang forces under Li Sheng and Hun Jian had launched a pincer attack from both east and west, repeatedly defeating Zhu Ci's rebel army. Zhu Ci selected five thousand elite troops and placed them under Zhang Guangsheng's command, stationing them at the Nine Bends region.
Zhang Guangsheng's army was stationed not far from Li Sheng's forces. Seeing that Zhu Ci was at the end of his rope, Zhang Guangsheng sent a trusted confidant to contact Li Sheng, expressing his willingness to surrender to the imperial court. Li Sheng welcomed Zhang Guangsheng's overture and simultaneously launched a massive assault on Chang'an, breaking through Baihua Gate.
As Zhu Ci saw the enemy forces advancing in full strength, he prepared to fight to the death. Zhang Guangsheng advised him, "Do not engage recklessly—flee westward to Jingzhou while you still can." Zhu Ci then led his remaining ten thousand troops, escorted by Zhang Guangsheng out of the city.
After seeing off Zhu Ci, Zhang Guangsheng turned back to pledge his allegiance to Li Sheng
However, Li Sheng's colleagues were displeased with how he treated Zhang Guangsheng as an honored guest. Lu Yuanguang, the military governor of Huazhou, even publicly pointed at Zhang Guangsheng and cursed, "I cannot sit at the same table as a rebel!"
With no other recourse, Li Sheng placed Zhang Guangsheng under house arrest, awaiting the court's judgment. Soon, Emperor Dezong issued an edict, declaring Zhang Guangsheng guilty of heinous crimes deserving execution. Unable to overturn the decree, Li Sheng had no choice but to carry out the sentence.
Zhang Guangsheng sighed before his death and said, "Tell future generations: first, do not start; second, do not stop."
This phrase means: if you're going to do something, you might as well see it through to the end.
Later, people used the idiom "If you do it at all, do it thoroughly" to mean either don't do it, or if you do, see it through to the end.
Source: *Fengtian Lu* by Zhao Yuanyi (Tang Dynasty)
Meaning of the Idiom: Later, the Chinese idiom "一不做，二不休" came to describe either don't do it, or if you do, see it through to the end.