攝大毘盧遮那成佛神變加持經入蓮華胎藏海會悲生曼荼攞廣大念誦儀軌供養方便會 2.49

2.49

前拳收火風，申水如來臍，
即前風火水，舒散如來腰，
二印各持明。

From the previous fist, retract the fire and wind [fingers], and extend the water [finger]: this is the Tathāgata-Navel.
Then, with the previous wind, fire, and water [fingers], extend and spread them: this is the Tathāgata-Waist.
Each of the two mudrās has its vidyā.