Shankaracharya's commentary, trans. Alladi Mahadeva Sastry (1897)
[1]Sin only would attach itself to us if we were to kill these aggressors. Therefore it is not right for us to kill the sons of Dhritarashtra and our kinsmen.
BG 1.36
पापमेवाश्रयेदस्मान् हत्वैतानाततायिनः। तस्मान्नार्हा वयं हन्तुं धार्तराष्ट्रान् सबान्धवान्॥
pāpam evāśrayed asmān hatvaitān ātatāyinaḥ / tasmān nārhā vayaṃ hantuṃ dhārtarāṣṭrān sabāndhavān
"Even the legal right to kill aggressors doesn't make it right — for Arjuna, love supersedes law."
3 translations · all pre-1928 or released to public domain · sources
Sin only would attach itself to us if we were to kill these aggressors. Therefore it is not right for us to kill the sons of Dhritarashtra and our kinsmen.
Sin would only attach to us if we were to kill these, although they are aggressors. Therefore we are not justified in slaying the sons of Dhritarashtra and our relatives.
Only sin would be ours if we killed these Dhritarashtraites who are our own relatives. We are not justified in slaying the sons of Dhritarashtra.