We bow unto that Prime State of Vishnu—that Supreme Deity—which is not known either to the deities, or the ascetics, or me, or Sankara himself. We bow unto that Supreme incomprehensible and indestructible State of Vishnu, which, on the exhaustion of their merits and demerits, the Yogis, ever persevering, view, grounded in the Pranava. We bow to the Prime State of that God Vishnu, who is without equal, and whose energy is Brahmā, Vishnu and Siva. O Lord of all! O soul of all beings! O thou that art all!

In plain words: Brahma says that not even the gods, the sages, he himself or Shiva (Sankara) fully know Vishnu's highest state. Dedicated yogis glimpse it through the sacred sound Om once their good and bad deeds are used up. Brahma, Vishnu and Shiva are all forms of his power.