Chapter 6 · The Yoga of Meditation · Krishna said
Bhagavad Gita 6.15 — Supreme peace
युञ्जन्नेवं सदात्मानं योगी नियतमानसः। शान्तिं निर्वाणपरमां मत्संस्थामधिगच्छति ॥
yuñjannevaṃ sadātmānaṃ yogī niyatamānasaḥ | śāntiṃ nirvāṇaparamāṃ matsaṃsthāmadhigacchati ||
Meaning
Constantly uniting himself in this way, with a disciplined mind, the yogi reaches the supreme peace of nirvana that rests in me.