《太平广记·卷十八·神仙十八》
唐太宗贞观年间，华阴的云台观有一个姓刘的法师绝了食修炼道家的闭气之功，一炼就是二十年。
唐贞观中，华阴云台观有刘法师者，炼气绝粒，迨二十年。
During the reign of Emperor Taizong of the Tang Dynasty, there was a Master Liu in the Yuntai Temple in Huayin who had given up food and cultivated the Taoist art of holding his breath. He had practiced for twenty years.