Chapter 17 · The Three Kinds of Faith · Krishna said
Bhagavad Gita 17.14 — Austerity of body
देवद्विजगुरुप्राज्ञपूजनं शौचमार्जवम्। ब्रह्मचर्यमहिंसा च शारीरं तप उच्यते ॥
devadvijaguruprājñapūjanaṃ śaucamārjavam | brahmacaryamahiṃsā ca śārīraṃ tapa ucyate ||
Meaning
Honouring the gods, the learned, teachers and the wise, along with cleanliness, simplicity, self-restraint and non-violence — this is called austerity of the body.