大毘盧遮那成佛經疏 17.28

17.28

第五月從金輪至水，同等諸佛處金剛水輪中。謂作方黃漫荼羅，內有圓白漫荼羅，身坐其中。臍以下黃，中以上白也。中不作印，用阿、嚩二字，餘如上。此五月中不得食，盡不食。謂斷一切食，但以二真言作出入息為食也。自五月以來，修無著離我之行，同於一相寂滅，即同佛也。

In the fifth month, going from the gold circle to water, equal to all buddhas, one dwells within the vajra-water circle. That is, form a square yellow maṇḍala containing a round white maṇḍala, with one's body seated within. Below the navel is yellow, and from the middle up is white. Inside, form no mudrā, but use the two syllables A and VA; the rest is as above. During these five months, one must not eat; all food is abstained from. That is, cutting off all food, one takes only the two mantras as the in-and-out breath for nourishment. From the fifth month onward, practicing the conduct of non-attachment and freedom from self, identical to the quiescent single characteristic, one is equal to the buddhas.