There is a passage in Mahabharata Anusasana Parva Section XLI that states:
Then the lady endeavoured to answer him. Vipula, however restrained the words she intended to utter. The words, therefore, that actually escaped her lips (under the influence of Vipula) were, ‘What is the reason of thy coming hither?’ These words adorned with grammatical refinements, issued out of her mouth that was as beautiful as the moon.
Ganguli, the translator, remarks that ‘Ladies spoke in Prakrita and not in Sanskrit. The latter is refined, the former is unrefined. Hence Indra’s surprise at hearing Sanskrit words from the lady’s lips.'