Vishnupurana 2.15.35

2.15.35

evamekamidaṃ viddhi na bhedi sakalaṃ jagat /
vāsudevābhidheyasya svarūpaṃ paramātmanaḥ //

"Having heard these words, conveying the substance of ultimate truth, Nidágha fell at the feet of his visitor, and said, 'Shew favour unto me, illustrious Brahman, and tell me who it is that for my good has come hither, and by whose words the infatuation of my mind is dissipated.' To this, Ribhu answered, 'I am Ribhu, your preceptor, come hither to communicate to you true wisdom; and having declared to you what that is, I shall depart. Know this whole universe to be the one undivided nature of the supreme spirit, entitled Vásudeva.' Thus having spoken, and receiving the prostrate homage of Nidágha, rendered with fervent faith, Ribhu went his way."