During the Tang Dynasty, there lived a monk named Wuda (809 – 882 AD), who was awarded the Kokushi title (an honorary title given to Buddhist masters) by the emperor.
Before he was awarded the Kokushi title, Wuda met a monk who was ill one day in a monastery. The monk had boils all over his body. He was filthy and emitted an awful odor. Everyone avoided him except for Wuda. He took pity on the sick monk and took care of him. Gradually, the monk returned to health. Before they parted, the monk thanked Wuda and said, "If you ever run into any tribulation, please look for me at Jiulong Mountain, in Pengzhou, Sichuan Province. You need to look for two pine trees next to each other."
Because Wuda had high moral values and conducted himself virtuously, Emperor Tang Yizhong (833 – 873 AD) respected him greatly. The emperor awarded him the title of Kokushi, and treated him very well. However, one day a boil with the shape of a human face grew on Wuda Kokushi's knee. It had facial features including a mouth and teeth. It could even swallow food when fed. Famous physicians from all over the country came to treat Wuda Kokushi's illness, but to no effect.
Wuda Kokushi suddenly remembered one day the sick monk he had nursed back to health. The monk had offered to help during times of tribulation before he departed, so Wuda went to the mountain to find him. By evening, he found the two pine trees next to each other. They were so tall that they seemed to reach into the sky. The monk was already waiting for him outside a grand, golden palace. The monk was very hospitable and asked Wuda to stay.
Wuda Kokushi told the monk about his strange and painful illness. The monk replied, "Don't worry about it. There is pristine spring water below the mountain cliff. Tomorrow morning, use the spring water to wash your knee, and you will be healed."
The next day, Wuda Kokushi went to the spring early in the morning. Just when he was about to scoop up some water, the boil with the human face shouted loudly, "Wait a minute! Do not wash yourself yet. You are knowledgeable and well read. Have you read the story of "Yuan Ang and Chao Cuo" in the books about the Western Han Dynasty?"
Wuda Kokushi replied, "Yes, I have read the story."
The boil said, "Since you know the story, how could you not remember that Yuan Ang killed Chao Cuo? You were Yuan Ang in your past life, and I was Chao Cuo. You denigrated me before the emperor and I was executed. I've been trying to seek revenge life after life. However, because you were a monk of high morality and conducted yourself well according to the commandments, I have not been able to take revenge. In this lifetime, you are much favored by the emperor and you’ve grown attached to fame and wealth. Your moral character has not been up to par therefore, I'm able to take revenge. Now that venerable Kanaka-vatsa Arhat (who transformed himself into the sick monk) is offering me the Samadhi water to set me free, let us dissolve our old grudges as well!"
Wuda Kokushi was frightened after hearing the story. He quickly scooped some water to clean the boil. The pain was so excruciating that he fainted. After he woke up, the boil on his knee was gone. When he turned around to look for the grand palace, it had disappeared without a trace. Wuda Kokushi later settled in that area to cultivate and never left. This is the story of the famous "Samadhi Water Repentance." Wuda Kokushi passed it down to future generations.
Although Wuda Kokushi had been a monk with high morality for ten lifetimes, he could not avoid the karmic retribution from an enmity formed ten lifetimes prior, simply because his moral character was deteriorating and he was yearning for fame and profit.
This true story certainly serves as a warning not to disregard a single thought. Moreover, who can doubt the fairness of the law of karmic retribution?