Bhagavad Gita · Chapter 17: The Three Kinds of Faith
Bhagavad Gita 17.27
यज्ञे तपसि दाने च स्थितिः सदिति चोच्यते ।
कर्म चैव तदर्थीयं सदित्येवाभिधीयते ॥
yajñe tapasi dāne ca sthitiḥ saditi cocyate | karma caiva tadarthīyaṃ sadityevābhidhīyate ||
Steadfastness in sacrifice, austerity, and giving is also called "Sat," and any action done for that purpose is likewise called "Sat."
Modern context
Steadfastness in sacrifice, discipline and giving is called 'Sat', and any action done for that purpose is too. Note the word 'steadfastness'. One good act is good; a life of steady goodness is something more. Consistency turns occasional virtue into character. And even ordinary actions done in support of such a life share in its goodness.