How can you be happy after killing a family member?
Body trembling, ominous premonitions, the feeling that there is no good in killing anyone, meaningless victories and kingdoms, and the sin of destroying a family. Having accumulated all these reasons, Arjuna arrives at a clear conclusion: "Therefore..."
One should not kill the sons of Dhritarashtra, who are relatives. How can one be happy by killing their own family members? He believes that it is impossible to achieve happiness in this life or the next by killing those close to you. This is a tentative conclusion from Arjuna's perspective, and from here, he will further elaborate on the problems caused by the destruction of his clan.
Japanese Translation from the Geeta Press Edition - Chapter 1, Section 37: "How can one be happy by killing their own relatives?"
Let us kill the sons of Dhritarashtra, our relatives. How can we be happy by killing our own people, Madhava? || 37 ||
Vocabulary
"tasmāt" means "therefore."
"na arhāḥ vayam hantum" means, "We should not kill."
"dhārtarāṣṭrān" means "the sons of Dhritarashtra."
"svabāndhavān" means "our relatives."
"svajanam" means "one's own family."
"hi" is "because".
"katham hatvā sukhi nām" means, "How can we be happy by killing?"
"madhava" is a way to address Krishna.
Translation
"Therefore, O Madhava, we should not kill our relatives, the sons of Dhritarashtra."
Because, if we kill our own family members, how can we possibly be happy?
Annotated Translation
At the beginning of this section, by using the word tasmāt, which means "therefore," Arjuna is about to say the following.
Considering the sad mental and physical state I am in, and further considering the reasons why I have opposed going to war, and also considering other thoughts that arise within me, he clearly concludes this.
The Pandavas should not kill Duryodhana and other relatives in the Kaurava army.
It is completely inappropriate for them to do so.
In this world, nor in any future life, there is no possibility that the Pandavas will gain any happiness by killing those who are close to them.
Therefore, he said that he did not want to fight.