Duryodhana’s first words in the Gītā are to his teacher, Droṇa. He points at the other army and reminds Droṇa that it was arranged by Drupada’s son, Droṇa’s own student. In the Mahābhārata, that student is the one who kills him.
Going deeper
1.3 is the first thing Duryodhana says in the Gītā. After 1.2 tells us that he approached his teacher Droṇa, he asks Droṇa to look at the great Pāṇḍava army, arrayed by the son of Drupada, whom he calls Droṇa's intelligent disciple. The verse is a pointed remark, and it is aimed at the teacher: the one who arranged the opposing army is his own former student. 1.4 goes on to name the heroes in that army, great bowmen equal to Bhīma and Arjuna in battle, with Yuyudhāna, Virāṭa and Drupada. So the first speech in the book is a king speaking to his teacher about another of that teacher's students. Within the Gītā, the verse shows a leader choosing his words for the man he is addressing. Read it in chapter 1.