SB 4.24.17
sangamah khalu viprarse
siveneha saririnam
durlabho munayo dadhyur
asangad yam abhipsitam
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The great sage Vidura continued: O best of the brahmanas, it is very difficult for living entities encaged within this material body to have personal contact with Lord Siva. Even great sages who have no material attachments do not contact him, despite their always being absorbed in meditation to attain his personal contact.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Since Lord Siva does not incarnate himself unless there is some special reason, it is very difficult for an ordinary person to contact him. However, Lord Siva does descend on a special occasion when he is ordered by the Supreme Personality of Godhead. In this regard, it is stated in the Padma Purana that Lord Siva appeared as a brahmana in the Age of Kali to preach the Mayavada philosophy, which is nothing but a type of Buddhist philosophy. It is stated in Padma Purana:
mayavadam asac-chastram
pracchannam bauddham ucyate
mayaiva vihitam devi
kalau brahmana-murtina
Lord Siva, speaking to Parvati-devi, foretold that he would spread the Mayavada philosophy in the guise of a sannyasi brahmana just to eradicate Buddhist philosophy. This sannyasi was Sripada Sankaracarya. In order to overcome the effects of Buddhist philosophy and spread Vedanta philosophy, Sripada Sankaracarya had to make some compromise with the Buddhist philosophy, and as such he preached the philosophy of monism, for it was required at that time. Otherwise there was no need for his preaching Mayavada philosophy. At the present moment there is no need for Mayavada philosophy or Buddhist philosophy, and Lord Caitanya rejected both of them. This Krsna consciousness movement is spreading the philosophy of Lord Caitanya and rejecting the philosophy of both classes of Mayavadi. Strictly speaking, both Buddhist philosophy and Sankara’s philosophy are but different types of Mayavada dealing on the platform of material existence. Neither of these philosophies has spiritual significance. There is spiritual significance only after one accepts the philosophy of Bhagavad-gita, which culminates in surrendering unto the Supreme Personality of Godhead. Generally people worship Lord Siva for some material benefit, and although they cannot see him personally, they derive great material profit by worshiping him.