Shivastotravalli 1.13:
आमूलाद्वाग्लता सेयं क्रमविस्फारशालिनी। त्वद्भक्तिसुधया सिक्ता तद्रसाढ्यफलास्तु मे।।
"O kind Shankara! There are 4 types of Vani(way of communication) Para, Pashyanti, Madhyama and Vaikhari. Let the fruits of my Bhaktirasa (devotion) spread from my mouth which becomes charming by cultivating from Para, Pashyanti, Madhyama, and Vaikhari Vanis and your nectar like devotion."
Shivastotravalli 1.14:
शिवो भूत्वा यजेतेति भक्तो भूत्वेति कथ्यते। त्वमेव हि वपुः सारं भक्तैरद्वयशोधितम्।।
"O Swatmamaheshwer! Shashtra says to worship Shiva become Shiva. But the devotees believe that one should worship by becoming your devotee since you, in non-dualistic form, are found by your devotees only from their devotion. And this is the way of worship should be accepted."
Akshay Ji: Devotion to Lord Shiva is ultimate. Devotion means Lord Shivas words is your life and thats called devotion. Such devotion is literally the highest knowledge.
MindDissolved Ji: the four states of Vāni (speech or sound) – Parā (the spiritual sound of Brahman), Madhyama (the cosmic sound of Vāstu=Purusha), Pashyanti (the semi-cosmic sounds of Vibhootis) and Vaikhari (the gross-level sounds of gross objects and living beings) bhakti will enabled bhakti in all four vani's. My Lord my god is so generous on his bhaktas that he enables bhakt in para vani.It is mentioned in Shasta's that to know Shiva is to be shiva, but bhakta are so occupied with surrendered devotion and love, that bhakta immersed in master and servant love story and wants to be in that state.