Mbh 5.7.1b

And, O Krishna, you stand at the very top of all right-minded persons in the world, and are always respected. I ask you to follow the rule of conduct observed by rightminded men.’ Thereat Krishna replied, ‘That you have come first, O king, I do not in the least doubt. But, O king, the son of Kunti, Dhananjaya, has been first beheld by me. On account of your first arrival, and on account of my having beheld Arjuna first, I shall, no doubt, lend my assistance, O Suyodhana, to both. But it is said that those who are junior in years should have the first choice. Therefore, Dhananjaya, the son of Kunti, is entitled to first choice. There is a large body of cowherds numbering ten crores, rivalling me in strength and known as the Narayanas, all of whom are able to fight in the thick of battle. These soldiers, irresistible in battle, shall be sent to one of you and I alone, resolved not to fight on the field, and laying down my arms, will go to the other. You may, O son of Kunti, first select whichever of these two commends itself to you. For, according to law, you have the right to the first choice.’”