Chapter 2 · The Yoga of Knowledge · Krishna said
Bhagavad Gita 2.25 — No cause for grief
अव्यक्तोऽयमचिन्त्योऽयमविकार्योऽयमुच्यते। तस्मादेवं विदित्वैनं नानुशोचितुमर्हसि ॥
avyakto'yamacintyo'yamavikāryo'yamucyate | tasmādevaṃ viditvainaṃ nānuśocitumarhasi ||
Meaning
The soul is called unseen, beyond thought and unchanging. Knowing it to be so, you should not grieve.