Rig veda 6.11.2

त्वं होता मन्द्रतमो नो अध्रुग् अन्तर् देवो विदथा मर्त्येषु |
पावकया जुह्वा वह्निर् आसाग्ने यजस्व तन्वं तव स्वाम् ||

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tvaṃ hotā mandratamo no adhrug antar devo vidathā martyeṣu |
pāvakayā juhvā vahnir āsāgne yajasva tanvaṃ tava svām ||

- tvaṃ hotā mandratamo no adhrug : You (agni/soul) are the priest (for the sacrifice conducted by the mortal being) who never harms and provides delight

- antar devo vidathā martyeṣu : You (agni/soul) are the god indwelling the mortal and helps him discover the knowledge
- pāvakayā juhvā vahnir āsāgne: By the purifying flame of oblation carried (to gods) in your mouth (symbolically the mantras chanted by the priest who is agni) 

- yajasva tanvaṃ tava svām: sacrifice (to gods) your own body (of the mortal man since you are it's indwelling soul)