Gita

Bhishma said I will fight for ten days. In those ten days I will not leave anyone, even if Krishna and Arjuna come.
Duryodhana was happy.

At the start, Krishna, holding his conch shell, Panchajanya, in both hands, blew it loudly. Pandavas blew their own conch shells.
Arjuna asked Krishna, Whom should we attack first?
Krishna took the chariot in the middle of the ground. Arjuna saw all his relatives there. He was not sure how he would be able to kill them. Gandiva fell from his hands. He said to Krishna I see all my dear ones here. How will I fight them?  Saying this, Arjuna sat down.
Krishna said This is your duty to fight. Who can kill whom? All is my doing? I am the One who is doing this. You talk of death. What is death apart from the soul leaving an old vessel and taking a new one. Soul is invincible, body gets destroyed.
I am the principal among all. All are in Me and I am in all.

Krishna and Arjuna spoke a lot which became known as Bhagwad Gita. Krishna explained the different yogas and about the philosophy of life.

Arjuna said I want to see your true form.
Arjuna saw the Great form of Krishna with the entire Universe in Him.

Arjuna picked up his bow.