Mahabharata Santi Parva Chapter 351:2

Mahabharata Santi Parva (Mokshadharma Parva) Chapter 351:2 "'Rudra said, "O illustrious one, through thy grace, all is well with my penances and Vedic studies. It is all right, again, with the universe. I saw thy illustrious self a long while ago in thy own home of felicity and effulgence. I am coming thence to this mountain that is now the abode of thy feet.[] Great is the curiosity excited in my mind by this withdrawal of thyself into such a lone spot from thy usual region of felicity and splendour. Great must the reason be, O Grandsire, for such an act on thy part. Thy own foremost abode is free from the pains of hunger and thirst, and inhabited by both deities and Asuras, by Rishis of immeasurable splendour, as also by Gandharvas and Apsaras. Abandoning such a spot of felicity, thou residest alone in this foremost of mountains. The cause of this cannot but be grave." "'Brahma said, "This foremost of mountains, called Vaijayanta, is always my residence. Here, with concentrated mind, I meditate on the one universal Purusha of infinite proportions." "'Rudra said, "Self-born thou art. Many are the Purushas that have been created by thee. Others again, O Brahma, are being created by thee. The Infinite Purusha, however, of whom thou speakest, is one and single. Who is that foremost of Purushas, O Brahma, that is being meditated by thee? Great is the curiosity I feel on this point. Do thou kindly dispel the doubt that has taken possession of my mind." "'Brahma said, "O son, many are those Purushas of whom thou speakest. The one Purusha, however, of whom I am thinking, transcends all Purushas and is invisible. The many Purushas that exist in the universe have that one Purusha as their basis; and since that one Purushas is said to be the source whence all the innumerable Purushas have sprung, hence all the latter, if they succeed in divesting themselves of attributes, become competent to enter into that one Purusha who is identified with the universe, who is supreme, who is the foremost of the foremost, who is eternal, and who is himself divested of and is above all attributes.