Mahabharata 7.110.20

दृष्ट्वा भ्रातॄन्हतान्युद्धे भीमसेनेन दंशितान्आत्मापराधात्सुमहन्नूनं तप्यति पुत्रकः

dṛṣṭvā bhrātṝnhatānyuddhe bhīmasenena daṃśitānātmāparādhātsumahannūnaṃ tapyati putrakaḥ

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