Bhagavad Gita · 18.54

ब्रह्मभूतः प्रसन्नात्मा न शोचति न काङ्क्षति।समः सर्वेषु भूतेषु मद्भक्तिं लभते पराम्॥

brahma-bhūtaḥ prasannātmā na śhochati na kāṅkṣhati samaḥ sarveṣhu bhūteṣhu mad-bhaktiṁ labhate parām

Having become Brahman, serene in the Self, one neither grieves nor desires. Regarding all beings equally, one attains supreme devotion to Me.

— Bhagavad Gita 18.54

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