Verse 19

व्याप्तं वासनया यत्स्याद्भूया जननमुक्तया ।जीवन्मुक्तमनःसत्ता राम तत्सत्त्वमुच्यते

In plain words

O Rāma, that which is pervaded by a vāsanā free from further birth -- that existence of the jīvanmukta's mind -- is called sattva.