I wanted to know whether shastras say otherwise ie viṣṇu being the greatest Śaiva. I always see Vaiṣṇava Katha vachakas constantly quoting from Śrīmad Bhagavatam about Śiva being limited to only Vaiṣṇava !!
Yes, Sastras Indeed speak of Sri Hari as Parama Śaiva
Kūrma Purāṇa directly states Sri Kṛṣṇa as the greatest devotee of Mahādeva along side Arjuna and Sri Vyāsa
Kūrma Purāṇa I.30.65
Padma Purāṇa too beautifully describes how Sri Hari donned Sacred Ash (Bhasma) and Asked For The Boon of having Eternal Śivabhakti from Mahādeva at the beginning of creation itself.
Padma Purāṇa Pātāla-Khaṇḍa Chapter 105
हरिरुवाच- न शक्तिं भस्मनो जाने प्रभावं वा कुतस्तव । नमस्तेऽस्तु नमस्तेऽस्तु त्वामेव शरणं गतः २३४। सदाशिव उवाच- वरं वृणु महाभाग मनसा यं > त्वमिच्छसि । शिववाचमथाकर्ण्य हरिर्वव्रे वरोत्तमम् २३५। हरिरुवाच- त्वत्पादयुगले शंभो भक्तिरस्तु सदा मम । अथ दत्वा वरं शंभुरिदमाह वचो हरिम् २३६। भस्मधारणसंपन्नो मम भक्तो भविष्यसि ।
- I do not know the power of the sacred ash, or whence can I know your prowess? Salutation to you, salutation to you. I seek your refuge. Śiva said:
235. O illustrious one, ask for a boon which you desire with (i.e. have in) your mind. Having then heard the words of Śiva, Viṣṇu chose an excellent boon. Viṣṇu said:
236-239. O Śambhu, let me always have devotion for the couple of your feet. Then having granted the boon Śambhu said these (words) to Viṣṇu: “Being happy with the application of the sacred ash, you will be my devotee.”
Often the question posted by you arises in the mind of most devoted persons, persons of Brahmin origin & Persons who feel in heart why there are Shaivaite & Vaishnavaite cults though both live alike? THESE ARE JUST NATURAL HUMAN TENDENCIES because we see different temples in different areas. HINDUISM IS ULTRA CLEAR: There is a clear truth about Gods & Goddesses in Hinduism. PARAMAATMA is one for all AATMAs on Earth, but forms of Supreme is diffirent because humans must be happy with colours & forms.
Human form of Maheshwara(God Shiva) is half mountainous and peak face with Serpent & Shoola. Human form of Mahodaya (God Vishnu) is resting posture on Aadishesha Naaga with Gods & Goddesses in milky ocean. Human form of Mahaapurusha (God Brahma) is meditative on skies with four heads in four directions E S N W
God Form need not worship other form but the explanation is "A FORM WORSHIPPED "PARAMAATMAN-SUPREME" ONLY THROUGH ANOTHER FORM SCIENTIFICALLY". Hence we, born as humans may or may not be powerful but we worship through any of God's form to realise Supreme happiness in oneself.
Yes, Lord Vishnu is said Not only a devotee of Bhagawan Shiva but the best among the leaders of Bhagawan Shiva's devotees.
Sri Skanda Purana 1.3b.4.:
54b-56.: There is no greater holy place other than Śoṇādri. There is no greater Mantra than the five-syllabled Mantra (Namaḥ Śivāya). There is no cult (greater) than the cult of Maheśvara. There is no god greater than Maheśvara. There is no better knowledge than the realization of Śiva. There is no Veda greater than Śrī Rudra. There is no greater leader of the devotees of Śiva than Viṣṇu. There is no greater protective factor than the sacred ash. There is no greater good conduct than the practice of devotion.
Sri Shiva Purana 5.1.:
- O Kṛṣṇa, great devotee of Śiva (Mahā Śaiva), listen to the glory of Śiva which I have witnessed myself. It is excellent story that enhances devotion to Śiva.
Even Bhagawan Shiva confirmed it.:
"With truth, purity, sincerity, resignation, ascetic austerities, vows, forgiveness, devotion, patience, thought, and word, I have been duly adored by Krishna of pure deeds. For this there is none dearer to me than Krishna".
I hope this clarifies all your queries. Prd..