Śivasaṃhitā 5.89

When Sarasvatī dances on the yogi’s tongue, every uttered word becomes mantra. This is not ordinary eloquence but speech invested with śakti: words emerge directly from the source of wisdom, without ego’s distortion. This state is the natural fruit of deep contemplation of the anāhata, the heart lotus.

Vaktra designates the mouth and face, Sarasvatī is the goddess of wisdom, arts and sacred speech (saras = fluid/lake, vatī = possessing), nṛtyati «dances» in present continuous, indicating permanence. Nirbharam means freely, without weight or restriction. The reference to Brahmā as keeper of the secret elevates this practice above the cosmic creative level.

The association of the heart lotus with the goddess of speech (Sarasvatī) apparently contradicts its usual identity as the vāyu (air) lotus. But in tantric cosmology, the heart is the seat of supreme vāk (parāvāk): speech prior to sound, where thought and expression are identical. When the yogi dwells in that center, their outer expression carries that same integrity.