Arjuna does not want to kill his kinsmen. Mahabharata 134

Raghu would say, almost challenge, I am waiting to see how you deal with Krishna's 'Gitopadesha!'
It is not difficult as Vachana Bharata, the version I follow, has dealt with it very briefly.

My questions were, once I learnt that Gita was originally enunciated by  Krishna on the first day of the great war, how long did it take him to reveal this gem of  hindu philosophy, called the Upanishad of  Upanishads?  Did Arjuna really grasp it one hearing?  Most would dismiss it as irrelevant questions and a few would claim that it all happened in the blink of an eye and tell me both 'Krishna and Arjuna were not just ordinary humans'. Anyway it was lucky for us that Sanjaya heard and Vyasa divined Bhagavad Gita and included it in Mahabharata.

Before I get back to the Vachana Bharata there are a few nuggets from Kamala's version:
The warriors on either side met and set the rules of the war: The fight should be between equals, two archers, two charioteers and so on. If during the fight if one withdrew he should not be harassed. If one fought with words, he should not be attacked with arrows! Anyone who runs away should not be killed. Charioteers, animals and servants who blow the trumpet or beat the drums should not be attacked.

The night before the war, Vyasa meets Dhritharashtra and offers him eyesight if he wants to see the war and Dhritharashtra declines the offer as he does not want to see his sons die. He would be satisfied if he could hear about it. So Vyasa gifts Sanjaya with ability to see everything that happens in the war. Hear their spoken words and even know their thoughts. 'He will see the battle in the day and relate it to you in the night. He will know no fatigue and exhaustion.' He tells Dhritarashtra that the omens prophesies the death of kauravas and the victory of pandavas, comforts his unhappy son and leaves.

... Yudhisthira sheds his armour and drops his weapons and goes barefoot towards kauravas. Perplexed his brothers follow him. Yudhisthira approaches Bheeshma and seeks his blessings as war is now about to begin. Bheeshma is pleased to bless him and says that the pandavas are assured of a victory. Yudhisthira then goes to his gurus Drona, Kripa  and Salya and is blessed by them as well.

Meanwhile Krishna goes to Radheya with an offer that as he is not fighting along with Bheeshma, he could join pandavas, at least till Bheeshma is killed and then join Duryodhana again. Radheya laughs  and requests Krishna to let him meet his fate with the kauravas. Krishna leaves saddened at the thought that Karna, a great hero, would die in a few days.

Then Yuyutsu one of the brothers of Duryodhana seeks to join pandavas and Yudhisthira welcomes him with the words that there will be at least one son from Kauravas who would perform rites when Dhritarashtra dies. These words spreads gloom amogst the kauravas.

To continue with Vachana Bharata:
Krishna moves the chariot to the centre of Kurukhsetra and Arjuna looks around and spots his grandfather, uncles, cousins and his gurus. Looking at them his heart melts. 'Krishna is it really right to kill my own relatives for the sake of the kingdom?  I do not want it. I will not fight even if I am offered the three worlds. There is no fun in killing your own kin. They are without sense and are greedy and are ready to fight even if it means the destruction of our clan. Should we  be like them? It is a great sin! It is better to live as a beggar than acquire wealth by killing your own elders and teachers. It is better that kauravs kill me!'   Full of sadness, Arjuna then  drops his weapons and sits still!.