Mu Yu was a native of Nanheping Xiang, Julu. His mother was poor and lowly; she assisted in childbirth. He once visited a woman in labor, and when the child was born it immediately opened its eyes, looked at his mother, and laughed loudly. At night she dreamed of a man with a large hat and red head covering guarding the child, who said: "This is Lord Siming, the Taoist deity of fate and destiny. He should repay your kindness by making your son Mu Yu attain immortality." The mother secretly believed and remembered this. Later, when the mother gave birth to a son, she named him Mu Yu. The child whom he had visited was fifteen years old; at night, carriages and horses came to take him away to Taoist immortality. He then passed by the mother's home and called out: "Mu Yu, Mu Yu, I have come as a charioteer!" And so they both left together, having completed the Three Fives cultivation required for ascension. More than twenty years later, a stork brought a two-chi-long fish at dawn and placed it on the mother's doorstep — an auspicious Taoist omen. The mother concealed this without speaking of it, but sold the fish. Thirty years later he finally disappeared. The mother lived to be a hundred and then died.

Lord Siming is very spiritual; the birth mother was shocked. Thus, he wanted to repay her and fulfill his promise, but it had not yet been completed. With cultivation sufficient for the Three Fives, light carriages came at night to welcome him. Ultimately repaying virtue, he lived long and was blessed with an extended life.