Sanskrit
यज्ञे तपसि दाने च स्थितिः सदिति चोच्यते । कर्म चैव तदर्थीयं सदित्येवाभिधीयते ॥
yajñe tapasi dāne ca sthitiḥ sad iti cocyate karma caiva tadarthīyaṃ sad ity evābhidhīyate
Translation
Steadfastness in sacrifice, austerity and gift is also called "Sat", and action for the sake of the Supreme is also named "Sat."
Annie Besant · The Bhagavad-Gita, translated by Annie Besant (4th ed., 1922) — Wikisource · Public Domain
Explanation
This verse folds the whole chapter back together: sthiti, steadfastness, in exactly the three domains graded across verses 11-22 — sacrifice, austerity, gift — is itself called Sat, and so is any action performed tad-arthīyam, for the sake of That (Tat, i.e. Brahman). “Goodness” is being redefined here not as an isolated property an act either has or lacks, but as consistency in offering one’s action toward the Absolute — which is precisely what distinguished the sattvic form of every category this chapter has surveyed.