Chapter 17 · verse 26 · gita.yoga.org

Bhagavad Gita 17.26

सद्भावे साधुभावे च सदित्येतत्प्रयुज्यते।प्रशस्ते कर्मणि तथा सच्छब्दः पार्थ युज्यते

The word "Sat" is used to refer to reality and goodness; likewise, O Arjuna, the word "Sat" is used to refer to an auspicious act.