Śatapatha Brāhmaṇa ("of a hundred paths") 1.3.4.16

1.3.4.16

so 'bhimṛśati | dhruvā asadanniti dhruvā hyasadannṛtasya yonāviti yajño vā ṛtasya yoniryajñe hyasadaṃstā viṣṇo pāhi pāhi yajñam pāhi yajñapatimiti tadyajamānamāha pāhi māṃ yajñanyamiti tadapyātmānaṃ yajñānnāntareti yajño vai viṣṇostadyajñāyaivaitatsarvam paridadāti guptyai tasmādāha tā viṣṇo pāhīti

He touches the offerings, with the text (Vâg. S. II, 6), 'Safely they have sat down,' for safely indeed they sat down;--'in the lap (yoni) of divine truth!' for the sacrifice is indeed the lap of divine truth, and in the sacrifice they sat down;--'Protect these, O Vishnu! protect the sacrifice! protect the lord of sacrifice!' thereby he refers to the sacrificer;--'Protect me, the leader of the sacrifice!' thereby he does not exclude himself either from the sacrifice. Vishnu, assuredly, is the sacrifice: hence it is to the sacrifice that he makes all that over for protection. This is the reason why he says, 'Protect these, O Vishnu!'