Bhagavad Gita 17.14
देवद्विजगुरुप्राज्ञपूजनं शौचमार्जवम्। ब्रह्मचर्यमहिंसा च शारीरं तप उच्यते।।17.14।।
devadvijaguruprājñapūjanaṃ śaucamārjavam| brahmacaryamahiṃsā ca śārīraṃ tapa ucyate||17.14||
devadvijaguruprajnapujanam shaucamarjavam brahmacaryamahimsa ca shariram tapa ucyate17.14
Meaning
Worship of the gods, teachers, the wise, and the learned; purity, straightforwardness, celibacy, and non-violence — these constitute the austerity of the body.
देव, द्विज, गुरु और ज्ञानीजनों का पूजन, शारीरिक शुद्धता, सरलता, ब्रह्मचर्य, और अहिंसा; यह सब शारीरिक तप कहलाता है।
This is verse 14 of 28 in Chapter 17 (Shraddhatraya Vibhaga Yoga) of the Bhagavad Gita.