यया तु धर्मकामार्थान् धृत्या धारयतेऽर्जुन। प्रसङ्गेन फलाकाङ्क्षी धृतिः सा पार्थ राजसी ॥

yayā tu dharma-kāmārthān dhṛityā dhārayate ‘rjuna prasaṅgena phalākāṅkṣhī dhṛitiḥ sā pārtha rājasī

But the firmness, O Arjuna, by which, from attachment desirous of fruit, one holdeth fast duty, desire and wealth, that firmness, O Pârtha, is passionate.

In plain words: Firmness ruled by passion holds tightly to duty, pleasure and wealth. It does this because it is attached and wants rewards.