Chapter 17 · The Three Kinds of Faith · Krishna said
Bhagavad Gita 17.17 — Sattvic austerity
श्रद्धया परया तप्तं तपस्तत्त्रिविधं नरैः। अफलाकाङ्क्षिभिर्युक्तैः सात्त्विकं परिचक्षते ॥
śraddhayā parayā taptaṃ tapastattrividhaṃ naraiḥ | aphalākāṅkṣibhiryuktaiḥ sāttvikaṃ paricakṣate ||
Meaning
When this threefold austerity is practised with deep faith by steady people who want no reward, it is called sattvic.