大毘盧遮那成佛經疏 17.29

17.29

Next, in the sixth month, one dwells in the wind and fire circles, eliminating all hindrances. This also means there is a fire circle within the wind circle; following the principle above, below is the wind, and from the navel above is fire. Taking HA and RA as nourishment, whether offered or not, one eats no food at all, having completely abandoned gain and sustenance.