Persons who have realized it have studied that the planets known as Pātāla constitute the bottoms of the feet of the universal Lord, and the heels and the toes are the Rasātala planets. The ankles are the Mahātala planets, and His shanks constitute the Talātala planets.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
पातालमेतस्य हि पादमूलं पठन्ति पार्ष्णिप्रपदे रसातलम् । महातलं विश्वसृजोऽथ गुल्फौ तलातलं वै पुरुषस्य जङ्घे
pātālametasya hi pādamūlaṃ paṭhanti pārṣṇiprapade rasātalam | mahātalaṃ viśvasṛjo'tha gulphau talātalaṃ vai puruṣasya jaṅghe
SB 2.1.26