Bhagavad Gita 1.36
निहत्य धार्तराष्ट्रान्नः का प्रीतिः स्याज्जनार्दन। पापमेवाश्रयेदस्मान्हत्वैतानाततायिनः।।1.36।।
nihatya dhārtarāṣṭrānnaḥ kā prītiḥ syājjanārdana| pāpamevāśrayedasmānhatvaitānātatāyinaḥ||1.36||
nihatya dhartarashtrannah ka pritih syajjanardana papamevashrayedasmanhatvaitanatatayinah1.36
Meaning
He asks what pleasure could come from killing Dhritarashtra's sons, and asserts that only sin would accrue from slaying these aggressors, despite their wrongdoing.
हे जनार्दन! धृतराष्ट्र के पुत्रों को मारकर हमें क्या प्रसन्नता होगी? इन आततायियों को मारने से तो हमें पाप ही लगेगा।
This is verse 36 of 47 in Chapter 1 (Arjuna Vishada Yoga) of the Bhagavad Gita.