Zhang Rui, Military Instructor of Chengzhou, courtesy name Zigang, was renowned for his medical skills and resided in Zhengzhou. During the Zhenghe era, the granddaughter-in-law of Duke Cai Lu fell ill at her expected delivery date. Physicians from the Imperial Medical Bureau diagnosed it as Yang-pattern Shanghan (Cold Damage characterized by heat syndromes) and, fearing miscarriage, dared not administer cooling agents. Duke Cai Lu secretly invited Zhang Rui to examine the patient. Zhang Rui stated, "The fetus has been in the womb for ten months and is about to be born; what medicine could cause failure?" He then prescribed medication according to standard methods and instructed the patient to double the dosage. Half a day later, the infant became ill and died. The following day, the woman suffered severe diarrhea and throat obstruction preventing food intake. Other physicians pointed out this error, stating that these two ailments were as contradictory as ice and charcoal, and since she had just given birth, even if Bian Que were reborn, there would be no hope of survival. Zhang Rui said, "Do not worry; I will cure her on the same day." He entered the room, took dozens of pills, and had her swallow them. Her throat immediately cleared, and the diarrhea stopped. By the full month postpartum, Duke Cai Lu hosted a banquet inviting sixty guests, including sons, grandsons, daughters, daughters-in-law, nephews, and sons-in-law, with Zhang Rui as the honored guest. The Duke personally poured wine to toast him, saying, "Your medical skill is divine. I dare not presume to understand, but may I ask how one medicine cured two different diseases?" Zhang Rui replied, "This is not recorded in the classics; it was my own judgment. What I used previously was Fuzi Lizhong Wan (Aconite Pill to Regulate the Middle) wrapped in Zixue (Purple Snow). At that time, the throat was blocked; only a supreme cold agent could resolve it. Once swallowed, the Zixue dissipated completely, while the power of Aconite reached the abdomen. Thus, one dose cured both ailments." The Duke greatly admired this, presenting him with all the golden spoons and chopsticks from the table.

When Murong Yanfeng, Minister of Justice, served as Attendant Gentleman of the Secretariat, his mother fell ill, and he summoned Zhang Rui from Zhengzhou. Upon arrival, the patient had already passed away. It was June, hot weather, and preparations for burial were underway. Zhang Rui wished to enter and examine the body. Murong Yanfeng, unwilling and suspecting Zhang sought money, said, "Travel expenses will be fully compensated; there is truly no need to enter." Zhang Rui said, "Shanghan protocols mention cases of revival after death within twenty-four hours. Why hesitate to let me look?" Reluctantly, Murong Yanfeng allowed him entry. Seeing the family weeping uncontrollably, Zhang Rui lifted the face cloth, observed the patient, and called the coroner, asking, "Have you ever seen someone who died in summer with a ruddy complexion?" The coroner replied, "No. However, the patient has no sweat and cold extremities; this is not death. Fortunately, do not hurry to bury." Zhang Rui quickly exited, retrieved medicine, ordered two sheng of water boiled down to half a sheng, and administered it to the patient, instructing, "Guard her well. If she has a profuse stool at midnight, she will survive." Zhang Rui stayed at an inn. At midnight, the caregiver heard a vigorous sound; feces covered the mat, expelling over a dou of foul matter. The family rejoiced and knocked urgently to call Zhang Rui. He responded, "My body is weary today; I cannot rise, nor is it necessary. Medication can begin tomorrow." As dawn approached, he went out as if to relieve himself but instead ordered his carriage back to Zhengzhou. When Murong Yanfeng visited his residence, only one packet of Pingwei San (Calm the Stomach Powder) remained. His mother took it for several days and recovered well. Presumably, due to Murong's suspicion of greed, Zhang Rui left without explanation.

During the Shaoxing era, Zhang Rui drifted into Shu. Wang Shujian asked him, "How often does your skill achieve the ancient ideal of 'ten successes out of ten'?" He answered, "Not yet; only seven or eight times out of ten." "My eldest son fell ill. Pulse diagnosis and observation indicated extreme heat. I ordered Chengqi Tang (Chengqi Decoction) to be boiled for him. As I was about to give it, doubt arose, causing hesitation. Just as I was about to administer it, it felt as though someone pulled my arm to stop me. I held the cup and waited. Suddenly, the child trembled and palpitated. After covering him with cotton blankets four or five times, he stabilized slightly, sweating profusely. The next day, he recovered completely. Had I forced the medicine down his throat, he would have died. How can one claim miraculous healing? Mediocre doctors study formularies, knowing but a fraction, yet consider themselves sufficient. Alas, this is terrifying!" (From *Yijian Zhi*)