Shiva Purana
एवं त्रिप्रकृतौ मोहात्परस्परजयैषिणौ ॥ प्रोचतुर्निगमांश्चात्र प्रमाणे सर्वथा तनौ ॥ १९॥
O sage, thus starting a mutual clash due to delusion and desiring to conquer each other they asked the Vedas about truth.
english translation
evaM triprakRtau mohAtparasparajayaiSiNau ॥ procaturnigamAMzcAtra pramANe sarvathA tanau ॥ 19॥
hk transliteration by Sanscript