Mahabharata 1.216.21

वज्रनाभं ततश्चक्रं ददौ कृष्णाय पावकःआग्नेयमस्त्रं दयितं स च कल्योऽभवत्तदा

vajranābhaṃ tataścakraṃ dadau kṛṣṇāya pāvakaḥāgneyamastraṃ dayitaṃ sa ca kalyo'bhavattadā

Our plain-language meaning of this verse is waiting for scholar review.