Prescribed action that is performed thinking ‘must be done’, abandoning attachment and fruit — that abandonment is considered sāttvika, oh Arjuna.

Sāttvika abandonment: correct attitude toward niyata-karma. Kāryam iti — “must be done,” as duty, without consideration of like/dislike.

Saṅgaṃ tyaktvā phalaṃ caiva — abandoning attachment and fruit. The tyāga is internal, not abandonment of action but transformation of attitude. It is sāttvikaḥ — luminous, correct.