Bhagavad Gita 6.27 Chapter 6, Verse 27

प्रशान्तमनसं ह्येनं योगिनं सुखमुत्तमम् ।
उपैति शान्तरजसं ब्रह्मभूतमकल्मषम् ॥६.२७॥

praśāntamanasaṃ hyenaṃ yoginaṃ sukhamuttamam
upaiti śāntarajasaṃ brahmabhūtamakalmaṣam

Meaning

Supreme joy comes to the yogi whose mind is completely calm, whose passions are stilled, who is free from sin and has become one with Brahman.

Newly written by Bhajan Dhun — scholarly review in progress.

Reference: Bhagavad Gita 6.27 (Chapter 6, The Yoga of Meditation (Atma Samyama Yoga), Verse 27)