Bhagavad Gita 4.24
For him, the sacrifice is the Spirit; the Spirit and the offering are one; it is the Spirit that is sacrificed in its own fire, and the man, even in action, is united with God, since his mind never ceases to be fixed on Him while performing the act.
ब्रह्मार्पणं ब्रह्महविर्ब्रह्माग्नौ ब्रह्मणा हुतम्।
ब्रह्मैव तेन गन्तव्यं ब्रह्मकर्मसमाधिना॥brahmārpaṇaṃ brahmahavirbrahmāgnau brahmaṇā hutam|
brahmaiva tena gantavyaṃ brahmakarmasamādhinā||
English translation (above): Shri Purohit Swami (1935), public domain. Sanskrit text via github.com/gita/gita (Unlicense).