Bhagavad Gita · 6.2

यं सन्न्यासमिति प्राहुर्योगं तं विद्धि पाण्डव।न ह्यसन्न्यस्तसङ्कल्पो योगी भवति कश्चन॥

yaṁ sannyāsam iti prāhur yogaṁ taṁ viddhi pāṇḍava na hy asannyasta-saṅkalpo yogī bhavati kaśhchana

What they call renunciation, know that to be yoga, O son of Pandu. No one can become a yogi without renouncing selfish motives.

— Bhagavad Gita 6.2

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