Sanskrit
यस्मात्क्षरमतीतोऽहमक्षरादपि चोत्तमः । अतोऽस्मि लोके वेदे च प्रथितः पुरुषोत्तमः ॥
yasmāt kṣaram atīto 'ham akṣarād api cottamaḥ ato 'smi loke vede ca prathitaḥ puruṣottamaḥ
Translation
Since I excel the destructible, and am more excellent also than the indestructible, in the world and in the Veda I am proclaimed the Supreme Spirit.
Annie Besant · The Bhagavad-Gita, translated by Annie Besant (4th ed., 1922) — Wikisource · Public Domain
Explanation
Krishna now claims the title directly: because he exceeds both the perishable and the imperishable, he is proclaimed in the world and in the Veda as Purushottama, the highest Purusha. The logic is worth noting — supremacy is argued here by exclusion, beyond both categories named in verse 16, rather than by a positive description of what the third category actually is, which is characteristic of how the Gita tends to gesture at its most absolute claims rather than fully specify them.