Bhagavad Gita 3.15

कर्म ब्रह्मोद्भवं विद्धि ब्रह्माक्षरसमुद्भवम् |
तस्मात्सर्वगतं ब्रह्म नित्यं यज्ञे प्रतिष्ठितम्

Translation

The duties for human beings are described in the Vedas, and the Vedas are manifested by God Himself. Therefore, the all-pervading Lord is eternally present in acts of sacrifice.