The position of the nitya-siddhas is explained in the Padma Purāṇa in connection with the narration of the Supreme Personality of Godhead and Satyabhāmādevī. The Lord tells Satyabhāmā: "My dear Satyabhāmādevī, I have descended to this earthly planet by the request of Lord Brahmā and other demigods. Those who are born into this family of Yadu are all My eternal associates. My dear wife, you should not consider that My associates are ever separated from Me; they are My personal expansions, and as such, you must know that they are almost as powerful as I am. Because of their transcendental qualities, they are very, very dear to Me, as I am very, very dear to them." Anyone who becomes exhilarated by hearing of the pastimes of Lord Kṛṣṇa when He was present on this earth with His associates is to be understood as nitya-siddha, eternally perfect.
In the Tenth Canto, 14th Chapter, 30th verse, of Śrīmad-Bhāgavatam there is the statement: "How wonderful are the fortunate residents of Vṛndāvana, such as Nanda and the other cowherd men. The Supreme Personality of Godhead, the supreme Brahman, has actually become their intimate friend!"
A similar statement is there in the Tenth Canto, 26th Chapter, 10th verse, of Śrīmad-Bhāgavatam. When Lord Kṛṣṇa lifted Govardhan Hill, the cowherd men, under the protection of Lord Kṛṣṇa, became struck with wonder and went to Nanda Mahārāj and inquired from him, "My dear Nanda Mahārāj, how is it that we are so intensely attached to Kṛṣṇa, and Kṛṣṇa is also so affectionately attached to us? Does it mean that He is the supersoul of everyone?"
All of the residents of Vṛndāvana and Dvārakā—namely the cowherd men and the members of the Yadu family—are eternally perfect devotees of the Lord. As the Lord descends by His causeless mercy upon this planet, so, in order to help in the pastimes of the Lord, these devotees also come here. They are not ordinary living entities or conditioned souls; they are ever-liberated persons, associates of the Personality of Godhead. And, just as Lord Kṛṣṇa behaves like an ordinary man when He descends to this planet, so the members of the Yadu dynasty and the residents of Vṛndāvana execute activities just like ordinary men. But they are not ordinary men; they are as liberated as Lord Kṛṣṇa Himself.
In the Padma Purāṇa, Uttara-khaṇḍa section, it is stated: "Just as Lord Rāmacandra descends along with Lakṣmaṇa and Bharata, an expansion of Saṅkarṣaṇa,* so the members of the Yadu dynasty and the cowherd men of Vṛndāvana also descend with Lord Kṛṣṇa in order to join in the transcendental pastimes of the Lord. When the Supreme Lord returns to His eternal abode, His associates return with Him to their respective places. As such, these ever liberated Vaiṣṇavas are not bound by the material laws of birth and death."