In Harivamsa, Bhavishya parva, chapter 80, there is an incident of a pisacha named Ghantakarna, who was an ardent devotee of Lord Shiva, even to the extent that he engaged in insulting Lord Vishnu. But Later on, by the grace of Lord Shiva, he was able to understand the supremacy of Lord Vishnu. Thus he was able to attain mukti. It states:
“Once upon a time, I went to the abode of Kailasa, where Lord Shiva resides.There I engaged myself in glorifying Lord Shiva and worshiping him.”
“Being pleased with my worship, Lord Shiva became happy, and he told me to ask for some benediction. I requested him to give me mukti (Liberation or moksha).”
“Hearing me asking for Mukti, Lord Shiva said that the the giver of Mukti is only Lord Vishnu, of this there should be no doubt.”
“Lord Shiva told me to go the Badari tirtha and staying in the hermitage of Nara-narayana sages, worship Lord Janardana.”
“Being told thus by Lord Shiva, I considered Lord Vishnu to be supreme and came here to stay in this place, to ask for the benediction of Mukti.”
The above incident is the part of the discussion between Ghantakarna and Lord Krishna. It proves that Lord Shiva cannot give Mukti to those who don’t understand that Lord Vishnu is supreme. The word “visnur eva na samsayah” is an emphatic statement used by Lord Shiva to prove that only Lord Krishna can grant Moksha. and no one else.
In Brihat Brahma samhita 3.9.68 (Pancharatra-samhita), Lord Shiva says to Gautama muni:
“ Lord Narayana is even superior to me and he alone can give moksha to everyone.”
In Brihat Brahma samhita 3.9.32, Lord Shiva further states:
“O King , I’m not the giver of Moksha. By nature, I’am subservient to lord Vishnu. Whereas Lord Vishnu is completely independent and the paramatma (supersoul) of all the living entities.”
In Skanda Purana, Lord Shiva tells Karttikeya:
“The statements of the Shaiva scriptures should be accepted only when they agree with the Vaishnava scriptures. Lord Vishnu is the only Supreme Lord, and knowledge of Him is the path to liberation. That is the conclusion of all the scriptures. Any other conclusions are meant only to bewilder people.”
In Harivamsa 3.89.5, Lord Shiva states:
“Only Lord Krishna is giver of Moksha.”
Once upon a time, Lord Shiva performed severe penance for the period of one year to worship Lord Vishnu. Then Lord Shiva obtained the vision of the Lord Vishnu, and asked the boon to obtain the power to give mukti to others. Thus Lord Shiva became Muktidata (giver of Moksha). This incident is mentioned in Padma Purana, uttara khanda,chapter 2.16.
Lord Shiva says to Narada Muni:
“By the mercy of Lord Vishnu, I became able to give Mukti to others.”
Lord Shiva is known to be the greatest of the Vaishnavas, thus he gives the knowledge of Lord Krishna to the devotees, and thereby people get Moksha. Narada Muni, the Prachetas (as described in Srimad Bhagavatam), and many other sages of the ancient past have considered Lord Shiva as their spiritual master, and they learned the science of Bhagavata dharma from Lord Shiva.
When Lord Shiva is pleased with such devotees’ unflinching and unmotivated devotional service, Lord Krishna is also pleased. Just as the guru is considered non-different from God, similarly Lord Shiva is considered non-different from Lord Krishna.
In Narada pancaratra 2.5.9, Narada identifies the non-difference of Lord Shiva and Lord Vishnu. But Lord Shiva then immediately clarifies that this non-difference is on account of Lord Shiva being a guru, and a disciple understands the guru to be non-different from Lord Krishna.The non-difference is not on account of absolute identity of svarupa.
It is stated in Narada pancharatra 2.5.12–13 as follows:
Lord Shiva says to Narada:
“A disciple who is highly religious, intelligent, a good Brahmana, pure and born of a noble family considers his guru equal to Lord Krishna. And that vile wretch who considers any other Demigod equal to Krishna, is quite illiterate, and certainly commits the sin of Brahmahatya.”
Thus the above verses explain non-difference in proper perspective, and simultaneously condemns equating any devata with Lord Krishna.
Lord Shiva, as the giver of jnana, and Lord Krishna, as the giver of Moksha, are explained as follows in the Skanda Purana:
“Seek Knowledge from Lord Shiva and liberation from Lord Janardana.”
Lord Shiva is the best of the Vaishnavas, and therefore he is the best of yogis, and best of jnanis. This fact is stated in Narada Pancaratra 1.1.63:
“Lord Shiva is the best of Vaishnava, best of yogi, best amongst the knowers of the absolute truth, and the best among all siddhas.”
When scriptures describe that Lord Shiva gives the Taraka Brahma mantra to those who die in Varanasi. This Taraka Brahma mantra is known to be the names of Lord Rama.Thus by chanting the names of Lord Rama, Lord Shiva becomes able to give Mukti to them.
Padma purana,svarga khanda,chapter 33.46,54 states:
“Lord Shiva, who is the Isvara of all, gives the taraka brahma (rama nama) mantra to those who die in Varanasi.”
“In Varanasi,those who obtain the jnana (knowledge of Lord Vishnu, taraka brahma) from Lord Mahadeva,they get liberated.”
Narada Pancaratra 2.7,46,47 states:
“Brahmana,go quickly to Lord Shankara, the ocean of knowledge and obtain Hari bhakti from him, as spoken by Vaisnavas, that will cut like an ax the severe bonds of Samsara.”
” Go and adopt Lord Shankara as your guru and obtain Hari bhakti from him. By attaining Hari bhakti, one will cross over samsara. The guru is brahman, and he acts like the helmsman to cross the ocean of samsara.”
Thus the above two verses from the Narada Pancharatra ask all devotees to obtain Hari Bhakti from Lord Shiva, who acts as the guru for all Vaishnavas.