Chapter 15 · The Supreme Person · Krishna said
Bhagavad Gita 15.11 — A pure heart sees
यतन्तो योगिनश्चैनं पश्यन्त्यात्मन्यवस्थितम्। यतन्तोऽप्यकृतात्मानो नैनं पश्यन्त्यचेतसः ॥
yatanto yoginaścainaṃ paśyantyātmanyavasthitam | yatanto'pyakṛtātmāno nainaṃ paśyantyacetasaḥ ||
Meaning
Yogis who strive see this Self within themselves. But those whose hearts are not purified and who lack understanding cannot see it, even if they try.