Meaning ARJUN FURTHER SAYS IN A BEWILDERED TONE: “Sin will overcome us ,if we slay such terrorising aggressors. So it is not proper for us to kill the sons of Dhritrastra and our friends. We won’t gain anything, O Krishna, married to the goddess of fortune, and how could we be happy by killing our own kinsmen?” ExplanationArjun is speaking of the guilt,that shall grow on the minds all his  life.As a person  shall be angry in the beginning but after the passage of time ,shall become dissolved in guilt of killing the ones, whom he loved once upon a time. Vedic injunction cautions against six type of oppressors, poison giver, one who sets fire to the house, one who attacks with deadly weapons ,one who plunders riches, one who occupy other’s land, one who kidnaps wife.such oppressers can be killed but this doubt came in Arjuna mind due to the virtue of saintliness thinking they were all his relative. Arjuna could have taken them all ,without even giving a thought but was relative with compassion.