yajñe tapasi dāne ca sthitiḥ saditi cocyate |karma caiva tadarthīyaṃ sadityevābhidhīyate ||
Steadfastness in sacrifice, in austerity, and in giving is also called "sat"; and action done for the sake of these is likewise spoken of as "sat".
Explanation
Krishna is continuing his explanation of "Om Tat Sat," the threefold name for the Absolute (Brahman). Here he extends the word "sat" (meaning real, good) to steady commitment in sacrifice (yajña), austerity (tapas) and giving (dāna), and to any action done in service of them. Commentators differ on whether "tadarthīya" means action for the sake of these three practices or for the sake of the Supreme; the verse supports both readings.