Chapter 17 · verse 27 · gita.yoga.org

Bhagavad Gita 17.27

यज्ञे तपसि दाने च स्थितिः सदिति चोच्यते।कर्म चैव तदर्थीयं सदित्येवाभिधीयते

Steadfastness in sacrifice, austerity, and gift is also called 'Sat', and action in connection with these, or for the sake of the Supreme, is also called 'Sat'.