Mahabharata 3.218.20

3.218.20

śakra uvāca |
yadi satyamidaṃ vākyaṃ niścayādbhāṣitaṃ tvayā |
yadi vā śāsanaṃ skanda kartumicchasi me śṛṇu || 20 ||

Indra replied, 'At thy bidding, O powerful being, I shall continue to act as Indra. And if thou hast said this deliberately and in earnest, then hear me how thou canst gratify thy desire of serving me. Do thou, O mighty being, take the leadership of the celestial forces accordingly.'