坐禪三昧經 2.19

2.19

The body is truly anitya, duḥkha, aśubha, and anātman, yet because the mind is subject to viparyāsa, it regards it as permanent, blissful, self, and pure. For this reason, in every respect one craves and is attached to one's body; such are base sentient beings. Because the practitioner wishes to destroy viparyāsa, they should practice the four applications of mindfulness: Contemplate the body in its various aspects, with its many sufferings and afflictions. Born of causes and conditions, it is therefore anitya; because of varied distress, it is therefore duḥkha; because the body contains thirty-six substances, it is therefore aśubha; because it does not have mastery, it is therefore anātman. Practicing such contemplation—contemplating the internal body, contemplating the external body, contemplating the internal and external body—practicing such contemplation is called mindfulness of the body.