Yoga Sutras of Patanjali · 3.55

सत्त्वपुरुषयोः शुद्धिसाम्ये कैवल्यम्॥५५॥

sattva-puruṣayoḥ śuddhi-sāmye kaivalyam

When sattva (the purified mind) and Purusha (the Self) attain equality of purity, liberation arises.

— Yoga Sutras of Patanjali 3.55

Source: Sanskrit attributed to Patanjali (c. 2nd century BCE – 4th century CE). Public-domain English readings drawn from Swami Vivekananda's 'Raja Yoga' (1896) and Charles Johnston's 'The Yoga Sutras of Patanjali' (1912).