Mahabharata 3.135.24

घोरेण तपसा राजंस्तप्यमानो महातपाःसंतापयामास भृशं देवेन्द्रमिति नः श्रुतम्

ghoreṇa tapasā rājaṃstapyamāno mahātapāḥsaṃtāpayāmāsa bhṛśaṃ devendramiti naḥ śrutam

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