Jie Cao Xian Huan (Knotting Grass and Holding Rings in the Mouth)
Wei Wuzi, the father of Wei Ke, an official of the State of Jin during the Spring and Autumn Period, had a favorite concubine. When the old man fell ill he instructed his son to marry her off to someone else in case of his death. But later, as his condition worsened, he told Wei Ke to kill her after he died and place her beside him in his grave so that they could be together in the afterlife. However, after his father's death, Wei Ke did not kill the woman, but let her remarry. He explained his action by saying, "When a person is sick to the point of death, he is not responsible for his words. I obeyed my father's will expressed when he was still of sound mind."
Later, when locked in heated combat with Du Hui, commander of an army of the State of Qin, he noticed a strange old man busily knotting tufts of grass on the battlefield. Du Hui's horse stumbled on one of the traps, and Du Hui was captured. That night Wei Ke dreamt that the same old man appeared to him, saying, "I am the father of the woman whose life you spared. I have repaid your merciful kindness."
A similar moral is contained in the story, Holding Rings in the Mouth:
During the Han Dynasty a nine-year-old boy named Yang Bao saw a flock of owls attacking a yellow bird. The yellow bird fell to the ground, whereupon it was attacked by ants. Yang Bao rescued the bird, took it home and took care of it. One day, when it was well again, the bird flew away. That same night Yang Bao dreamt that a boy clad all in yellow appeared to him holding four jade rings in his mouth. The apparition said, "I am a herald of the Western Queen Mother of the Gods. In return for your rescuing me, I present you with these rings. Your descendants will be as pure as these rings and will rise to high rank."
Sure enough, Yang Bao's son, grandson and great-grandson all became senior officials.