यस्मात्क्षरमतीतोऽहमक्षरादपि चोत्तमः। अतोऽस्मि लोके वेदे च प्रथितः पुरुषोत्तमः ॥

yasmāt kṣharam atīto ’ham akṣharād api chottamaḥ ato ’smi loke vede cha prathitaḥ puruṣhottamaḥ

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.

In plain words: Krishna says that because he is greater than both the perishable and the imperishable, the world and the holy books call him the Supreme Person.