Shiva Purana
भूतादिर्महता तद्वदव्यक्तेनावृतो महान् ॥ एतैरावरणैरण्डं सप्तभिर्बहिरावृतम् ॥ ३५ ॥
The Bhūtādi is enveloped by the Mahat. The Mahat is enveloped by Avyakta. Thus the egg is enveloped by even coverings.
english translation
bhUtAdirmahatA tadvadavyaktenAvRto mahAn ॥ etairAvaraNairaNDaM saptabhirbahirAvRtam ॥ 35 ॥
hk transliteration by Sanscript