Shiva Purana
एवं तृतीयावरणे वितते पूजिते सति ॥ चतुर्थावरणं ध्यात्वा बहिस्तस्य समर्चयेत् ॥ २४ ॥
When the third Āvaraṇa has been worshipped thus he shall worship the fourth Āvaraṇa outside it after meditation.
english translation
evaM tRtIyAvaraNe vitate pUjite sati ॥ caturthAvaraNaM dhyAtvA bahistasya samarcayet ॥ 24 ॥
hk transliteration by Sanscript