Astanga Hrudaya
तामसं भयमज्ञानं निद्राऽऽलस्यं विषादिता। इति भूतमयो देहः तत्र सप्त त्वचोऽसृजः॥८॥
fear, ignorance, sleep, laziness and grief are tamasa (derivations from tarmoguna) thus the body is composed of the bhutas. Satpa tvacha- the seven skins: The body has seven layers of skin are produced during the cooking
english translation