Chapter 17 · The Three Kinds of Faith · Krishna said
Bhagavad Gita 17.27 — Action for God
यज्ञे तपसि दाने च स्थितिः सदिति चोच्यते। कर्म चैव तदर्थीयं सदित्येवाभिधीयते ॥
yajñe tapasi dāne ca sthitiḥ saditi cocyate | karma caiva tadarthīyaṃ sadityevābhidhīyate ||
Meaning
Steadiness in sacrifice, austerity and charity is also called 'Sat', and any action done for God's sake is called 'Sat' too.