Mahabharata 9.10.56

ततः सुमनसः पार्था भीमसेनमपूजयन्तद्दृष्ट्वा कर्म संग्रामे घोरमक्लिष्टकर्मणः

tataḥ sumanasaḥ pārthā bhīmasenamapūjayantaddṛṣṭvā karma saṃgrāme ghoramakliṣṭakarmaṇaḥ

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