Chapter 13 · The Field and the Knower · Krishna said
Bhagavad Gita 13.23 — The Supreme Self as witness
उपद्रष्टानुमन्ता च भर्ता भोक्ता महेश्वरः। परमात्मेति चाप्युक्तो देहेऽस्मिन्पुरुषः परः ॥
upadraṣṭānumantā ca bhartā bhoktā maheśvaraḥ | paramātmeti cāpyukto dehe'sminpuruṣaḥ paraḥ ||
Meaning
In this body there is also the Supreme Person — the witness, the one who permits, the supporter, the experiencer, the great Lord — who is called the Supreme Self.
In today's life
Devotees feel that they are never truly alone, because the inner witness is always present.