Brahma-saṁhitā (5.33) states:

advaitam acyutam anādim ananta-rūpam ādyaṁ purāṇa-puruṣaṁ nava-yauvanaṁ ca vedeṣu durlabham adurlabham ātma-bhaktau govindam ādi-puruṣaṁ tam ahaṁ bhajāmi

“I worship the Supreme Personality of Godhead, Govinda, who is the original person. He is absolute, infallible and beginningless, and although expanded into unlimited forms, He is still the same original person, the oldest person, who always appears as a fresh youth. The eternal, blissful, all-knowing forms of the Lord cannot be understood even by the best Vedic scholars, but they are always manifest to pure, unalloyed devotees.” Lord Śiva places himself as one of the nondevotees, who cannot understand the identity of the Supreme Lord. The Lord, being ananta, has an unlimited number of forms. Therefore, how is it possible for an ordinary, common man to understand Him? Lord Śiva, of course, is above the ordinary human beings, yet he is unable to understand the Supreme Personality of Godhead. Lord Śiva is not among the ordinary living entities, nor is he in the category of Lord Viṣṇu. He is between Lord Viṣṇu and the common living entity.