Dharma Master Wu Da was from Sichuan, China, and lived in the late Tang Dynasty. He became a Buddhist monk at the age of seven and was given the Dharma name, Zhi Xuan. When Zhi Xuan was young, he travelled around China to study Buddhism. While travelling, he stayed in a temple where he encountered a sick monk, whose body was covered with festering sores that emitted a foul odor. Everyone kept away from the monk, but Zhi Xuan stayed and nursed him back to health. Before they parted ways, the monk thanked Zhi Xuan and told him that if he ever encountered difficulties, he could look for him in Jiulong Mountain by two pine trees.
For many years, Zhi Xuan practiced diligently and mastered the Buddhist canon. He was thus held in high regard and respect by the emperor, who honored him with the title “Imperial Dharma Master Wu Da”. The emperor attended Master Wu Da’s lectures and even bestowed him with a precious gift, an agarwood chair, for him to sit on while lecturing.
Upon seeing the chair, a sense of arrogance arose in Master Wu Da. When he was about to take his seat, he bumped his knee on the chair. A bruised developed on his knee, and it became a terrible large sore shaped like a human face with eyes and a mouth. Master Wu Da suffered tremendous pain as a result. The emperor summoned doctors from all over the country to treat him, but none of them could find a cure. Then, Master Wu Da remembered the words of the sick monk he met decades ago and set off for Jiulong Mountain to look for him.
Upon seeing Master Wu Da, the monk told him to go to a spring at the foot of the mountain the next day and wash his sore with the spring water. The following day, just as Master Wu Da was about to rinse the sore, he heard a voice. It seemed to be the human-faced sore speaking. The voice spoke of a story from the Western Han Dynasty of how Yuan Ang, a government official, had the emperor executed Chao Cuo. Harboring great hatred for Yuan Ang, the soul of Chao Cuo followed him life after life, trying to find an opportunity to take revenge.
But, because for ten lifetimes, Yuan Ang was a monk who had cultivated purity of conduct, there was no chance for Chao Cuo to take revenge. And in this lifetime, Yuan Ang was Master Wu Da. Because Master Wu Da gave rise to arrogance, Chao Cuo was able to take his revenge on him as the human-faced sore.
The voice then told Master Wu Da that the monk he had helped nurse was Venerable Kanaka, who taught him to wash his sore with the Samadhi-water, which helped untie the knots of hatred in his (Chao Cuo’s) heart. After Master Wu Da rinsed the sore with the water, it healed completely.
When one has created negative karma, one will suffer the retribution resulting from it. Even though Master Wu Da has cultivated diligently for ten lifetimes, he still had to suffer retribution due to the bad karma he created in a past life. Realizing that, he gave up his high post in the court and stayed in Jiulong Mountain, where he built a cabin to repent for his wrongs. There, he composed the Water Repentance Text to remind people not to commit wrongdoings and to practice repentance for the wrongs they have committed.