रजो रागात्मकं विद्धि तृष्णासङ्गसमुद्भवम्। तन्निबध्नाति कौन्तेय कर्मसङ्गेन देहिनम् ॥

rajo rāgātmakaṁ viddhi tṛiṣhṇā-saṅga-samudbhavam tan nibadhnāti kaunteya karma-saṅgena dehinam

Motion, the passion nature, know thou, is the source of attachment and thirst for life, O Kaunteya, that bindeth the dweller in the body by the attachment to action.

In plain words: Krishna says passion creates strong wanting and craving. It ties the soul down by making it attached to always doing things.