Brihadaranyaka Upanishad 3.1.3

3.1.3

yājñavalkyeti hovāca yadidam̐ sarvaṃ mṛtyunāptam̐ sarvaṃ mṛtyunābhipannaṃ kena yajamāno mṛtyorāptimatimucyata iti hotrartvijāgninā vācā vāgvai yajñasya hotā tadyeyaṃ vākso'yamagniḥ sa hotā sa muktiḥ sātimuktiḥ

'Yâgñavalkya, he said, 'everything here (connected with the sacrifice) is reached by death, everything is overcome by death. By what means then is the sacrificer freed beyond the reach of death?'
Yâgñavalkya said: 'By the Hotri priest, who is Agni (fire), who is speech. For speech is the Hotri of the sacrifice (or the sacrificer), and speech is Agni, and he is the Hotri. This constitutes freedom, and perfect freedom (from death).'