Bhagavad Gita 1.36

My Lord! What happiness can come from the death of these sons of Dhritarashtra? We shall be committing a sin if we kill these desperate men.

निहत्य धार्तराष्ट्रान्नः का प्रीतिः स्याज्जनार्दन।
पापमेवाश्रयेदस्मान्हत्वैतानाततायिनः॥

nihatya dhārtarāṣṭrānnaḥ kā prītiḥ syājjanārdana|
pāpamevāśrayedasmānhatvaitānātatāyinaḥ||

English translation (above): Shri Purohit Swami (1935), public domain. Sanskrit text via github.com/gita/gita (Unlicense).