At the gods' urging the Sacrifice beckons Vac three times; she refuses twice and then calls him. Once she has come over, the gods take possession of her and offer her up as their own, and the Asuras, left without speech, can only cry out in sounds no one understands.
The Satapatha-Brahmana, tr. Julius Eggeling (Sacred Books of the East 12, 41) § 3.2.1.18-24
Sources: The Satapatha-Brahmana, tr. Julius Eggeling (Sacred Books of the East 12, 41)
The Adityas outwit the Angirases with a same-day Soma sacrifice, make them their priests, and pay them with the sun as a white horse.
Speech is the price paid to the Gandharvas for Soma, and returns to the gods because they sing.
Speech walks out on the gods, hides in the waters and the trees, and on another occasion becomes a lioness.
A hymn portrait of Vac from Rigveda 10.125, with what Rigveda 10.71, 8.100 and 1.164 say of her.
Mind and Speech each claim to be the better.