hatha yoga classical
You lie flat on your back, arms a little away from the body, palms up, legs loose and turned out, and stay completely still — the posture is named for a corpse because that is the degree of stillness intended. Nothing is tensed, nothing is stretched, nothing is counted. The Haṭha Yoga Pradīpikā gives it in a single line (1.32): lying like this removes the fatigue produced by the other practices and quiets the mind. It is the oldest instruction in this collection for doing nothing on purpose, and the one modern deep-rest recordings are descended from.