Where did Zhang Wuji's Seven-Wounded Boxing in Jin Yong's novel Eternal Dragon Slayer come from?

I learned this from my adoptive father Xie Xun, the Golden Lion King.

This matter should start from Xie Xun. Xie Xun, the Golden Lion King, was originally an apprentice of Cheng Kun, the thunderbolt of the Yuan Dynasty. Yang Dingtian, founder of Zoroastrianism, stole Cheng Kun's childhood sister. Cheng Kun fell in love with Yang Dingtian and vowed to avenge Yang Dingtian's destruction of Zoroastrianism at his sister's wedding. Yang Dingtian neglected Cheng Kun's school sister because he was addicted to Gankun in the secret passage, and Cheng Kun took the opportunity to have sex with her. School sister took Cheng Kun to the secret passage, and Yang Dingtian, who was practicing, saw them, and Yang Ding died directly in the weather. My younger sister felt sorry for Yang Dingtian and committed suicide.

Cheng Kun, who lost her school sister, has a stronger hatred and wants to destroy Zoroastrianism. At this time, disciple Xie Xun became one of the four kings of French Zoroastrianism, which was a pawn he could use. Cheng Kun defiled Xie Xun's wife and killed Xie Xun's wife and children. Xie Xun vowed to get back at Cheng Kun, but Cheng Kun seemed to disappear. Finally, Xie Xun began to go crazy, killing innocent people in Wulin. Every time he commits a crime, he leaves the words "Cheng Kun, thunderbolt". However, Cheng Kun ignored Xie Xun's actions and chose to remain invisible. It turned out that he hid in Shaolin Temple and became a monk's dharma name.

Cheng Kun thought that Xie Xun's affair could not arouse many sects' hatred of Zoroastrianism, so he robbed the Seven Injuries Boxing Spectrum of the Kongtong Sect and gave it to Xie Xun. Later, Xie Xun and Zhang Cuishan Yin Susu lived together on an island of ice and fire. Zhang Cuishan and Yin Susu fell in love and gave birth to Zhang Wuji. When Xie Xun heard Zhang Wuji crying, he was not crazy. Zhang Cuishan and Xie Xun became brothers, and Xie Xun became Zhang Wuji's adoptive father. In memory of Xie Xun's son Xie Wuji, the child was named Wuji. Xie Xun transferred all his love for his son to Zhang Wuji. Whenever he goes crazy, as long as Zhang Wuji calls him, he won't go crazy. Xie Xun also gave Zhang Wuji all his martial arts, including Seven Wounds Boxing.

Zhang Wuji's Seven Wounds Boxing was taught by his adoptive father Xie Xun, the Golden Lion King.