Srimad-Bhagavatam: Canto 11 - Chapter 1 - Verse 37

Sanskrit:

परिस्तीर्याथ पर्युक्षेदन्वाधाय यथाविधि ।प्रोक्षण्यासाद्य द्रव्याणि प्रोक्ष्याग्नौ भावयेत माम् ॥ ३७ ॥

ITRANS:

paristīryātha paryukṣedanvādhāya yathā-vidhiprokṣaṇyāsādya dravyāṇiprokṣyāgnau bhāvayeta mām

Translation:

After spreading kuśa grass on the ground and sprinkling it with water, one should perform the anvādhāna ritual according to the prescribed rules. Then one should arrange the items to be offered as oblations and should sanctify them with water from the sprinkling vessel. The worshiper should next meditate upon Me within the fire.

Purport:

Śrīla Jīva Gosvāmī mentions that one should meditate upon the Lord as the Supersoul within the sacrificial fire.