The Atharva Veda

The meaning is that he stands having transcended the region. "Ten fingers' breadth" is an indicator; he exists, having permeated even beyond the universe. With one part he has permeated the universe, and with ten parts he remains established in himself.

With three feet, he ascended; his one foot was here again. In that manner, he moved everywhere toward the things that eat and do not eat. || 2 ||

This sacrificial Nārāyaṇa Puruṣa ascended to the heavenly world with three feet—that is, three quarters. His fourth foot appears here in the earthly realm, manifesting again and again.

He demonstrates his pervasion of all worlds through these four feet. In that manner, he moved toward everything—the things that eat (humans, animals, etc.) and those that do not eat (deities, trees, etc.). He is the all-pervader.

From the spiritual perspective, this primordial person, with three feet or parts, ascended—that is, stood—in the self-luminous state of heaven, untouched by the world. Although the absolute Brahman is infinite and cannot be divided into four parts, the description of "feet" is used to imply that this world is very small compared to the nature of Brahman. He is the person without contact with the world, whose nature is knowledge; he stood in heaven. He remains in his own nature, untouched by the merits and faults of this place. His one foot—a mere fraction—appeared here in this world, manifesting again and again through creation and dissolution. The fact that this entire world is but a fraction of the Paramātman Supreme Soul is stated by the Lord himself: "I exist by supporting this entire universe with a single fraction of myself" (Bhagavad Gītā 10.42).