Yoga Sutras of Patanjali 3.30

नाभिचक्रे कायव्यूहज्ञानम् ॥

nabhi-chakre kaya-vyuha-jnanam

By samyama on the navel center, knowledge of the arrangement of the body arises.

नाभि-चक्र पर (संयम से) काय-व्यूह (शरीर-संरचना) का ज्ञान।