klaibyam ma sma gamah partha
naitat tvayy upapadyate
O son of Pritha, do not yield to this degrading impotence. It does not become you. Give up such petty weakness of heart and arise, O chastiser of the enemy.
Commentary by Srila Prabhupada
Arjuna was addressed as the son of Pritha, who happened to be the sister of Krishna’s father Vasudeva. Therefore Arjuna had a blood relationship with Krishna. If the son of a kshatriya declines to fight, he is a kshatriya in name only, and if the son of a brahmana acts impiously, he is a brahmana in name only. Such kshatriyas and brahmanas are unworthy sons of their fathers; therefore, Krishna did not want Arjuna to become an unworthy son of a kshatriya. Arjuna was the most intimate friend of Krishna, and Krishna was directly guiding him on the chariot; but in spite of all these credits, if Arjuna abandoned the battle he would be committing an infamous act. Therefore Krishna said that such an attitude in Arjuna did not fit his personality. Arjuna might argue that he would give up the battle on the grounds of his magnanimous attitude for the most respectable Bhishma and his relatives, but Krishna considered that sort of magnanimity mere weakness of heart. Such false magnanimity was not approved by any authority. Therefore, such magnanimity or so-called nonviolence should be given up by persons like Arjuna under the direct guidance of Krishna.
Commentary by Sri Visvanatha Cakravarti Thakur
“Do not become cowardly (klaibyam), impotent. O Partha, you are the son of Prtha, but in spite of that you have acted like this. Do not yield to this. This weakness should be checked even in the inferior ksatriyas, but in you, my friend, it is not proper at all.”
“Do not worry about my lack of bravery; do not think I am a coward. One must consider the precepts of dharma in regards to Bhisma, Drona and other elders, and also consider the aspect of compassion in regard to the sons of Dhrtarastra, who, being weaker than I, being afflicted by my weapons, are about to die.”
“This is not discretion based on dharma and mercy, but bewilderment and lamentation, indications of a weak mind (ksudram hrdaya daurbalyam). Therefore give up this weakness of mind and rise up. O conqueror of enemies (parantapa), you, who afflict enemies, fight!”