Bg 2.3

klaibyam ma sma gamah partha
naitat tvayy upapadyate
ksudram hrdaya-daurbalyam
tyaktvottistha paran-tapa

Word for word: 
klaibyam — impotence; ma sma — do not; gamah — take to; partha — O son of Prtha; na — never; etat — this; tvayi — unto you; upapadyate — is befitting; ksudram — petty; hrdaya — of the heart; daurbalyam — weakness; tyaktva — giving up; uttistha — get up; param-tapa — O chastiser of the enemies.

Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
O son of Prtha, 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.

Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Arjuna was addressed as the son of Prtha, who happened to be the sister of Krishna’s father Vasudeva. Therefore Arjuna had a blood relationship with Krishna. If the son of a ksatriya declines to fight, he is a ksatriya in name only, and if the son of a brahmana acts impiously, he is a brahmana in name only. Such ksatriyas and brahmanas are unworthy sons of their fathers; therefore, Krishna did not want Arjuna to become an unworthy son of a ksatriya. 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 Bhisma 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.