He couldn't see how any good could come of killing
He did not desire any subsequent victory, kingdom, or happiness.
A kingdom, happiness and even life itself would be useless when all those for whom he may desire them are killed.
He did not wish to kill them, even though they might kill him.
He was not prepared to fight with them even in exchange for the three worlds, let alone this earth.
He would derive no pleasure from killing the sons of Dhrtarastra.
It would be better to forgive them on grounds of religion and saintly behavior.
Greed, killing one's family and quarreling with friends is wrong
Destroying a family is sinful
Obligation is only binding when the effect is good
The eternal family tradition will be vanquished and the family will become involved in irreligion.
The women will become polluted and produce unwanted progeny.
This will cause hellish life both for the family and for those who destroy the family tradition.
The ancestors of such corrupt families fall down, because the performances for offering them food and water are entirely stopped.
All kinds of community projects and family welfare activities will be devastated.
Those who destroy family traditions will always dwell in hell.
He could not attack men worthy of his worship. "It would be better to live in this world by begging than to live at the cost of the lives of great souls who are my teachers. Even though desiring worldly gain, they are superiors. If they are killed, everything we enjoy will be tainted with blood."
If we kill the sons of Dhrtarastra, we should not care to live."
Reasons for fighting
No sin is incurred for killing six kinds of aggressors: (1) a poison giver, (2) one who sets fire to the house, (3) one who attacks with deadly weapons, (4) one who plunders riches, (5) one who occupies another's land, and (6) one who kidnaps a wife.
A ksatriya is not supposed to refuse a challenge. For a Ksatriya to decline a fight is non-Aryan.
Material compassion, lamentation and tears are all signs of ignorance of the real self. Compassion for the eternal soul is self-realization.
These impurities are not at all befitting a man who knows the value of life. They lead not to higher planets but to infamy. They are due to weakness of heart.
Krishna did not approve of this false magnanimity.
A teacher who engages in an abominable action and has lost his sense of discrimination is fit to be abandoned.
Because Bhisma and Drona took Duryodhana's side because of financial assistance, they have lost the respectability of teachers.
Those who are wise lament neither for the living nor for the dead.
A sober person is not bewildered by the soul's changing bodies.
Arjuna should rejoice for their changing bodies from old to new ones, thereby rejuvenating their energy.
Bhisma and Drona, being noble souls, were surely going to have spiritual bodies in the next life, or at least life in heavenly bodies for superior enjoyment of material existence. So, in either case, there was no cause of lamentation.
One must learn to tolerate the temporary appearances of happiness and distress.
The soul is eternal and can never be destroyed
For the administration of justice, violence is permitted, and is not sinful.
Killing their bodies in the righteous fight will cleanse them of all reactions from various bodily activities and promote them to a higher status of life.