brahmārpaṇaṃ brahmahavirbrahmāgnau brahmaṇā hutam |brahmaiva tena gantavyaṃ brahmakarmasamādhinā ||
The act of offering is Brahman, the oblation is Brahman, poured by Brahman into the fire that is Brahman. Brahman alone is reached by one who is absorbed in action that is Brahman.
Explanation
Krishna has just said that work done as sacrifice (yajña) leaves no binding trace on one who is free from attachment. Here he describes that sacrifice: the act of offering (which some commentators take as the ladle used to offer), the oblation, the fire and the one who offers are all seen as Brahman, the ultimate reality. Whoever is fully absorbed in this vision of action reaches Brahman. Advaita readers take it as the non-duality of all things, while devotional traditions read it as seeing everything as belonging to and sustained by the Divine.