Shiva Purana
महत्तत्त्वं समारभ्य शरीरं तु सहस्रकम् । एकैकस्माज्जपादेकमतिक्रम्य शनैः शनैः ४२ ।
Starting from the Mahat-tattva (the great principle), one should meditate on the body, which is like a thousand-petaled lotus. Gradually, step by step, one should focus on each part of the body, progressing slowly.
english translation
mahattattvaM samArabhya zarIraM tu sahasrakam । ekaikasmAjjapAdekamatikramya zanaiH zanaiH 42 ।
hk transliteration by Sanscript