Mahabharat
अग्नौ हुत्वा समुत्पाद्य घोर वृत्रमुवाच ह । इन्द्रशत्रो विवर्धस्व प्रभावात् तपसो मम ॥ ५-९-४८ ॥
He (Tvashtra) offered oblations into the fire. Having created the terrible Vritra, he told him, ‘O enemy of Indra! Through the strength of my asceticism, increase in power.’
english translation
agnau hutvA samutpAdya ghora vRtramuvAca ha । indrazatro vivardhasva prabhAvAt tapaso mama ॥ 5-9-48 ॥
hk transliteration by Sanscript