Bhagavad Gita 8.20
In truth, therefore, there is the eternal, unmanifest, which is beyond and above the unmanifest spirit of creation, and which is never destroyed when all these beings perish.
परस्तस्मात्तु भावोऽन्योऽव्यक्तोऽव्यक्तात्सनातनः।
यः स सर्वेषु भूतेषु नश्यत्सु न विनश्यति॥parastasmāttu bhāvo'nyo'vyakto'vyaktātsanātanaḥ|
yaḥ sa sarveṣu bhūteṣu naśyatsu na vinaśyati||
English translation (above): Shri Purohit Swami (1935), public domain. Sanskrit text via github.com/gita/gita (Unlicense).