Bhagavad Gita 5.20
न प्रहृष्येत्प्रियं प्राप्य नोद्विजेत्प्राप्य चाप्रियम्। स्थिरबुद्धिरसम्मूढो ब्रह्मविद् ब्रह्मणि स्थितः।।5.20।।
na prahṛṣyetpriyaṃ prāpya nodvijetprāpya cāpriyam| sthirabuddhirasammūḍho brahmavid brahmaṇi sthitaḥ||5.20||
na prahrishyetpriyam prapya nodvijetprapya capriyam sthirabuddhirasammudho brahmavid brahmani sthitah5.20
Meaning
One who neither rejoices upon obtaining something pleasant nor grieves upon receiving something unpleasant, who is steady in intellect, undeluded, and established in Brahman — such a person knows Brahman.
जो स्थिरबुद्धि, संमोहरहित ब्रह्मवित् पुरुष ब्रह्म में स्थित है, वह प्रिय वस्तु को प्राप्त होकर हर्षित नहीं होता और अप्रिय को पाकर उद्विग्न नहीं होता।
This is verse 20 of 29 in Chapter 5 (Karma Sanyasa Yoga) of the Bhagavad Gita.