Raja Vidya Guhya Yoga-Bhagavad Gita Chapter 9 [Confidential Knowledge of the Ultimate Truth]
Krishna Said > Shaloka: 16
English
But it is I who am the ritual, I the sacrifice, the offering to the ancestors, the healing herb, the transcendental chant. I am the butter and the fire and the offering.
Purport
The sacrifice known as jyotistoma is also Krishna, and He is also the maha-yajna. The oblations offered to the Pitrloka or the sacrifice performed to please the Pitrloka, considered as a kind of drug in the form of clarified butter, is also Krishna. The mantras chanted in this connection are also Krishna. And many other commodities made with milk products for offering in the sacrifices are also Krishna. The fire is also Krishna because fire is one of the five material elements and is therefore claimed as the separated energy of Krishna. In other words, the Vedic sacrifices recommended in the karma-kanda division of the Vedas are in total also Krishna. Or, in other words, those who are engaged in rendering devotional service unto Krishna are to be understood to have performed all the sacrifices recommended in the Vedas.