Sanskrit
तस्मान्नार्हा वयं हन्तुं धार्तराष्ट्रान्स्वबान्धवान् । स्वजनं हि कथं हत्वा सुखिनः स्याम माधव ॥
tasmān nārhā vayaṃ hantuṃ dhārtarāṣṭrān svabāndhavān svajanaṃ hi kathaṃ hatvā sukhinaḥ syāma mādhava
Translation
Therefore we should not kill the sons of Dhritarâshtra, our relatives; for how, killing our kinsmen, may we be happy, O Mâdhava?
Annie Besant · The Bhagavad-Gita, translated by Annie Besant (4th ed., 1922) — Wikisource · Public Domain
Explanation
A clean “therefore,” closing the argument built across verses 31–36: no victory, kingdom, or self-preservation justifies it, the people in question are kin on both sides, and killing them can’t lead to happiness anyway. Verses 38–39 immediately open a second, related argument on top of this one.