The great sage Maitreya said to Vidura: My dear Vidura, as soon as King Dakṣa offered the clarified butter with Yajur Veda mantras in sanctified meditation, Lord Viṣṇu appeared there in His original form as Nārāyaṇa.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
अध्वर्युणाऽऽत्तहविषा यजमानो विशाम्पते । धिया विशुद्धया दध्यौ तथा प्रादुरभूद्धरिः
adhvaryuṇā''ttahaviṣā yajamāno viśāmpate | dhiyā viśuddhayā dadhyau tathā prādurabhūddhariḥ
SB 4.7.18