Karika 19

तस्माच्च विपर्यासात् सिद्धं साक्षित्वमस्य पुरुषस्य। कैवल्यं माध्यस्थ्यं द्रष्टृत्वमकर्तृभावश्च ॥१९॥

Based on that (multiplicity of beings) and deformations (of three qualities) we can establish the Purusha as a witness. It also establishes the Purusha's eligibility to liberation, intermediary nature, the observer, and not the doer feeling.