Bhagavad Gita · 6.27

प्रशान्तमनसं ह्येनं योगिनं सुखमुत्तमम्।उपैति शान्तरजसं ब्रह्मभूतमकल्मषम्॥

praśhānta-manasaṁ hy enaṁ yoginaṁ sukham uttamam upaiti śhānta-rajasaṁ brahma-bhūtam akalmaṣham

Supreme happiness comes to the yogi whose mind is peaceful, whose passions are quieted, who is free from sin, and who has become one with Brahman.

— Bhagavad Gita 6.27

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