Mahabharata 5.73.21

इदं मे महदाश्चर्यं पर्वतस्येव सर्पणम्यदीदृशं प्रभाषेथा भीमसेनासमं वचः

idaṃ me mahadāścaryaṃ parvatasyeva sarpaṇamyadīdṛśaṃ prabhāṣethā bhīmasenāsamaṃ vacaḥ

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