Bhagavad Gita 1.3
पश्यैतां पाण्डुपुत्राणामाचार्य महतीं चमूम् । व्यूढां द्रुपदपुत्रेण तव शिष्येण धीमता ॥
paśyaitāṃ pāṇḍu-putrāṇām ācārya mahatīṃ camūm | vyūḍhāṃ drupada-putreṇa tava śiṣyeṇa dhīmatā ||
Translation
Behold, teacher, this great army of the sons of Pandu, arrayed by your gifted pupil, the son of Drupada.
Reflection
Who did you help grow into the person now standing across from you?
Read this verse in its chapter: Chapter One
Duryodhana's first specific point is a barb. Dhrishtadyumna, who marshals the Pandava army, was born for the express purpose of killing Drona. And he learned how to do it from Drona. A small thing here names a large life-shape. Every teacher meets former students on the other side eventually. Every parent watches a child use what they were taught to do something the parent would not have chosen. Nobody in the scene calls it tragic. It just is. The work travels.