大毘盧遮那成佛經疏 14.7

14.7

Next, extend the palm of the left hand, bend the two fingers earth and water into the palm, turn the wind finger to pinch the back of the fire finger, and slightly hook and bend the space finger; this is the Kaumārī Śakti mudrā (śakti is an implement mudrā; the drawings illustrate it). This is the son of Maheśvara named Kārttikeya, and this Kaumārī is his consort's name.