Mahabharat
शक्रं जहीति चाप्युक्तो जगाम त्रिदिवं ततः । ततो युद्धं समभवद् वृत्रवासवयो्महत् ॥ ५-९-५० ॥
Having been told that he should kill Shakra, he went to heaven. And next ensued a great fight between Vritra and Indra.
english translation
zakraM jahIti cApyukto jagAma tridivaM tataH । tato yuddhaM samabhavad vRtravAsavayomahat ॥ 5-9-50 ॥
hk transliteration by Sanscript