大毘盧遮那成佛經疏 17.24

17.24

復次如上所云，一味一味真實之見難信難解，如來復以異方便世間持誦之法而助真實見，故次說六月持誦法。然皆是祕密究竟，與前不異也。其第一月當觀金剛，是方漫荼羅，黃色也。觀其自身而坐此中，即以自身而作阿字。其a字正方黃色，當令內身充滿無缺，舉體皆是此字也。當結五股金剛印，不須持數珠。其印作虛心合掌，雙屈二水，以右加左相句掌中，二空雙並出，二風句屈向中指背，即是金剛手印也。當於一月中，但服乳不食餘物。但觀所持真言從臍而出、從鼻而入，如調喘息無異。爾時但觀以此真言而為喘息也，其色亦黃。若觀真言，即以一一句為一息。若觀種子字，但無間作息也。雖云一月，然一十一百乃至一落叉月等，要以見為限。復次一者即是一相一味之義也，見此名滿一月。

Furthermore, as stated above, the realization of reality as of a single flavor is difficult to believe and difficult to understand. The Tathāgata, by means of other upāyas consisting of worldly methods of recitation, assists this realization of reality; therefore he next expounds the method of six months of recitation. Yet these are all secret and ultimate, not different from what preceded. In the first month, one should visualize a vajra: it is a square maṇḍala, yellow in color. One visualizes one's own body seated within it, identifying one's body with the syllable A. The syllable A is square and yellow; one should make it fill the interior of the body completely without deficiency, so that the entire body is this syllable. One should form the five-pronged vajra mudrā without needing to hold a rosary. For this mudrā, make a hollow-palmed añjali, bend both water [ring] fingers and clasp them right over left inside the palms, extend both space [thumb] fingers together, and bend the two wind [index] fingers toward the backs of the middle fingers—this is the Vajrapāṇi mudrā. During this one month, consume only milk and eat no other food. Simply visualize the recited mantra emerging from the navel and entering through the nose, just like regulating the breath. At that time, visualize this mantra as the breath itself, its color also yellow. If visualizing the mantra, let each phrase be one breath. If visualizing the bīja syllable, simply breathe continuously. Although it is called one month, whether it takes ten, a hundred, or up to a lakṣa of months, the limit must be seeing. Furthermore, 'one' has the meaning of a single characteristic and a single flavor; seeing this is called completing one month.