पश्यैतां पाण्डुपुत्राणामाचार्य महतीं चमूम्। व्यूढां द्रुपदपुत्रेण तव शिष्येण धीमता ॥

paśhyaitāṁ pāṇḍu-putrāṇām āchārya mahatīṁ chamūm vyūḍhāṁ drupada-putreṇa tava śhiṣhyeṇa dhīmatā

"Behold this mighty host of the sons of Pându, O teacher, arrayed by the son of Drupada, thy wise disciple.

In plain words: Duryodhana tells his teacher Drona to look at the huge Pandava army. He points out that it was arranged by the son of Drupada, who was once Drona's own student.