Pls help. Title of short story from a book?

Hi, pls help

Does anyone know the title of the story about a man who wanted to become immortal, and he read about a ritual wherein he needed to excavate an area next to a specific tree, and the ritual required that he be buried face down when he died, but his didnt succeed because he was buried facing up (like normal people) because his assistant thought it indignifying if he was buried facing down?