What is Observing the Gengshen Day 守庚申?

Shou Gengshen, also known as "guarding the three corpses" or "beheading the three corpses", refers to sitting in meditation all night without sleeping on the Gengshen day to eliminate the three corpses. Hetu Jiming Fu states: "Heaven and earth have gods in charge of recording faults, who deprive people of their lifespan years according to the severity of their offences.

For major evil deeds, they deprive one ji (which equals one year); for minor offences, they deprive one suan (which equals one day)..." Taoism holds that governing the three corpses is essential for becoming an immortal. Therefore, various methods to govern the three corpses have been proposed, among which Shou Gengshen is one.