Bhagavad Gita 2.25

अव्यक्तोऽयमचिन्त्योऽयमविकार्योऽयमुच्यते।तस्मादेवं विदित्वैनं नानुशोचितुमर्हसि ॥२.२५॥

avyakto’yamacintyo’yamavikāryo’yamucyatetasmādevaṃ viditvainaṃ nānuśocitumarhasi

This Self is said to be unmanifested, unthinkable, and unchangeable. Therefore, knowing this to be so, you should not grieve.

गीता