Mahabharata 2.39.9

वैशंपायन उवाच · vaiśaṃpāyana uvāca

तस्य तद्वचनं श्रुत्वा रूक्षं रूक्षाक्षरं बहुचुकोप बलिनां श्रेष्ठो भीमसेनः प्रतापवान्

tasya tadvacanaṃ śrutvā rūkṣaṃ rūkṣākṣaraṃ bahucukopa balināṃ śreṣṭho bhīmasenaḥ pratāpavān

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