Srimad-Bhagavatam: Canto 2 - Chapter 1 - Verse 20

Sanskrit:

नाभ्यां स्थितं हृद्यधिरोप्य तस्मा-दुदानगत्योरसि तं नयेन्मुनि: ।ततोऽनुसन्धाय धिया मनस्वीस्वतालुमूलं शनकैर्नयेत् ॥ २० ॥

ITRANS:

nābhyāṁ sthitaṁ hṛdy adhiropya tasmādudāna-gatyorasi taṁ nayen muniḥtato ’nusandhāya dhiyā manasvīsva-tālu-mūlaṁ śanakair nayeta

Translation:

The meditative devotee should slowly push up the life air from the navel to the heart, from there to the chest, and from there to the root of the palate. He should search out the proper places with intelligence.

Purport:

There are six circles of the movement of the life air, and the intelligent bhakti-yogī should search out these places with intelligence and in a meditative mood. Among these, mentioned above is the svādhiṣṭhāna-cakra, or the powerhouse of the life air, and above this, just below the abdomen and navel, is the maṇi-pūraka-cakra. When upper space is further searched out in the heart, one reaches the anāhata-cakra, and further up, when the life air is placed at the root of the palate, one reaches the viśuddhi-cakra.