CC Madhya 20.312

śivaḥ śakti-yuktaḥ śaśvat
tri-liṅgo guṇa-saṁvṛtaḥ
vaikārikas taijasaś ca
tāmasaś cety ahaṁ tridhā
Synonyms: 
śivaḥ — Lord Śiva; śakti-yuktaḥ — associated with material nature; śaśvat — eternally; tri-liṅgaḥ — in three features; guṇa-saṁvṛtaḥ — covered by the modes of nature; vaikārikaḥ — one is called vaikārika; taijasaḥ ca — another is called taijasa; tāmasaḥ ca — as well as tāmasa; iti — thus; aham — egotism; tri-dhā — three kinds.
Translation: 
“ ‘The truth about Lord Śiva is that he is always covered with three material coverings — vaikārika, taijasa and tāmasa. Because of these three modes of material nature, he always associates with the external energy and egotism itself.’
Purport: 

This is a quotation from Śrīmad-Bhāgavatam (10.88.3).