Shiva Purana
परीक्षितुं च तद्भक्तिं शक्ररूपधरो हरः ॥ प्राह गंभीरया वाचा बालकन्तं मुनीश्वर ॥ २२॥
O great sage, in order to test his devotion, Śiva in the form of Indra, spoke to the boy in a grave tone.
english translation
parIkSituM ca tadbhaktiM zakrarUpadharo haraH ॥ prAha gaMbhIrayA vAcA bAlakantaM munIzvara ॥ 22॥
hk transliteration by Sanscript