Bhagavad Gita, Chapter 18, Verse 78

Wherever is Krishna, the Lord of Yoga, wherever is Pârtha, the wielder of the bow, there are prosperity, victory, expansion, and sound policy: such is my conviction.

Sanjaya ends the Gita with a confident claim: where Krishna and Arjuna stand together, victory follows.

Sanjaya, who has narrated the whole conversation, closes with his own conviction: where Krishna and Arjuna are together there is prosperity, victory and sound policy. The Gita ends on that concrete assurance.