Chapter 17 · verse 11 · gita.yoga.org

Bhagavad Gita 17.11

अफलाकाङ्क्षिभिर्यज्ञो विधिदृष्टो य इज्यते।यष्टव्यमेवेति मनः समाधाय स सात्त्विकः

That sacrifice which is offered by men without desire for reward, as enjoined by the ordinance (scripture), with a firm faith that doing so is their duty, is Sattvic or pure.