यतन्तो योगिनश्चैनं पश्यन्त्यात्मन्यवस्थितम्। यतन्तोऽप्यकृतात्मानो नैनं पश्यन्त्यचेतसः ॥

yatanto yoginaśh chainaṁ paśhyanty ātmany avasthitam yatanto ‘py akṛitātmāno nainaṁ paśhyanty achetasaḥ

Yogîs also, struggling, perceive Him, established in the Self; but though struggling, the unintelligent perceive Him not, their selves untrained.

In plain words: Krishna says that people who practice yoga and work hard at it, staying centered in their true self, do see the soul. But people who have not trained their minds do not see it, even when they try.