Bg 2.32

yadrcchaya copapannam
svarga-dvaram apavrtam
sukhinah ksatriyah partha
labhante yuddham idrsam

Word for word: 
yadrcchaya — by its own accord; ca — also; upapannam — arrived at; svarga — of the heavenly planets; dvaram — door; apavrtam — wide open; sukhinah — very happy; ksatriyah — the members of the royal order; partha — O son of Prtha; labhante — do achieve; yuddham — war; idrsam — like this.

Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
O Partha, happy are the ksatriyas to whom such fighting opportunities come unsought, opening for them the doors of the heavenly planets.

Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
As supreme teacher of the world, Lord Krishna condemns the attitude of Arjuna, who said, “I do not find any good in this fighting. It will cause perpetual habitation in hell.” Such statements by Arjuna were due to ignorance only. He wanted to become nonviolent in the discharge of his specific duty. For a ksatriya to be on the battlefield and to become nonviolent is the philosophy of fools. In the Parasara-smrti, or religious codes made by Parasara, the great sage and father of Vyasadeva, it is stated:

ksatriyo hi praja raksan
sastra-panih pradandayan
nirjitya para-sainyadi
ksitim dharmena palayet

“The ksatriya’s duty is to protect the citizens from all kinds of difficulties, and for that reason he has to apply violence in suitable cases for law and order. Therefore he has to conquer the soldiers of inimical kings, and thus, with religious principles, he should rule over the world.”

Considering all aspects, Arjuna had no reason to refrain from fighting. If he should conquer his enemies, he would enjoy the kingdom; and if he should die in the battle, he would be elevated to the heavenly planets, whose doors were wide open to him. Fighting would be for his benefit in either case.