Bhagavadgeeta Verse 3.15
कर्म ब्रह्मॊद्भवं विद्धि ब्रह्माक्षर समुद्भवम् ।
तस्मात् सर्वगतं ब्रह्म नित्यं यज्ञॆ प्रतिष्ठितम् ॥ ३.१५ ॥
ಕರ್ಮ ಬ್ರಹ್ಮೋದ್ಭವಂ ವಿದ್ಧಿ ಬ್ರಹ್ಮಾಕ್ಷರ ಸಮುದ್ಭವಮ್ |
ತಸ್ಮಾತ್ ಸರ್ವಗತಂ ಬ್ರಹ್ಮ ನಿತ್ಯಂ ಯಜ್ಞೇ ಪ್ರತಿಷ್ಠಿತಮ್ || ೩.೧೫ ||
karma brahmOdbhavaM viddhi brahmAkShara samudbhavam |
tasmAt sarvagataM brahma nityaM yaj~jE pratiShThitam || 3.15 ||
You should know that Karma has its source in Brahman; Brahman has its source in Akshara; The all-pervading Brahman is ever established in Yajna.
Brahman or the Supreme Lord from whom all activity proceeds, is revealed by the Vedas (also called “akshara” or the imperishable or the eternal testimony). Only when duty is known as it is through the Vedas, the Brahman enables the jeeva to do the righteous duty. That Brahman is to be revealed to us through yajna, since He is always present in it. So by performing yajna, the person is contributing to the revelation of the Supreme Being, in addition to contributing to the well being of all creatures.