Bhagavad Gita · Chapter 17: The Three Kinds of Faith

Bhagavad Gita 17.6

karṣayantaḥ śarīrasthaṃ bhūtagrāmamacetasaḥ | māṃ caivāntaḥśarīrasthaṃ tānviddhyāsuraniścayān ||

senselessly tormenting the elements that make up the body, and me as well, who dwell within the body: know them to be demonic in their resolve.

Modern context

Those who torment the body torment the divine that dwells within it. This is a striking reason to treat one's body with care. The body is not an enemy to be punished but a temple to be respected. Self-harm, whether through extreme discipline or through neglect, is described here not as holiness but as something closer to the demonic.