Mahabharata 8.49.109

अतः सत्यां प्रतिज्ञां तां पार्थेन परिरक्षतामच्छन्दादवमानोऽयं कृतस्तव महीपतेगुरूणामवमानो हि वध इत्यभिधीयते

ataḥ satyāṃ pratijñāṃ tāṃ pārthena parirakṣatāmacchandādavamāno'yaṃ kṛtastava mahīpategurūṇāmavamāno hi vadha ityabhidhīyate

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