Bhagavad Gita · 18.16

तत्रैवं सति कर्तारमात्मानं केवलं तु यः।पश्यत्यकृतबुद्धित्वान्न स पश्यति दुर्मतिः॥

tatraivaṁ sati kartāram ātmānaṁ kevalaṁ tu yaḥ paśhyaty akṛita-buddhitvān na sa paśhyati durmatiḥ

This being so, one who sees oneself alone as the doer, due to impure understanding, does not see truly — such a person is of perverted intelligence.

— Bhagavad Gita 18.16

Source: Sacred-Texts.com (Sanskrit) + Bhagavad-Gita.io (translations)