Yōga Sūtra 3.56

सत्त्वपुरुषयोः शुद्धिसाम्ये कैवल्यमिति।

sattvapuruṣayōḥ śuddhisāmyē kaivalyamiti।

[सत्त्व पुरुषयोः शुद्धि साम्ये कैवल्यम इति।
sattva = sātvik; puruṣayōḥ = when such a person; śuddhi = becomes pure; sāmyē = because of equanimity; kaivalyama = in kaivalaya; iti = said to be;]

When such sātvik person becomes pure because of equanimity, he is said to be in kaivalya.