長阿含經 18.p26

18.p26

“The Dharma that the Tathāgata teaches has another superiority, which is his attainments of vision. The attainments of vision refer to this: Ascetics and priests use various methods to enter a fixed samādhi of mind. Following that samādhi of mind, they visualize their head to their toes and observe their toes to their head. Inside and outside of their skin, there’s only impure hair, nails, the five organs of liver, lungs, stomach, spleen, and kidneys, sweat, fat, marrow, brain, feces, urine, tears, and foul-smelling places of impurity. Not one of them is desirable. This is the first attainment of vision.