SB 10.50.48

Kṛṣṇa uses the plural (vidhāsyāmaḥ -I will create) to show respect to Balarāma. We will place the Yadus there comfortably (sam—ādhāya). We will have him killed. They would not kill him so that Śiva’s boon would not be contradicted. Mucukunda would do it. The Lord’s reason is explained in Hari-vaṁśa. iyaṁ ca māthurī bhūmir alpā gamyā parasya tu / vṛddhiś cāpi parāsmākaṁ balato mitratas tathā // kumara-koṭyo yāś cemā gaṇāś caiva padātinām / eṣām apīha vasatāṁ saṁmardam upalakṣaye // Mathurā will be too small in the future for the increase of population from our and others’ armies, friends, and unlimited children. There is also a host of foot soldiers. The place will be crowded with all these people living here. This is what I think. Not only did Kṛṣṇa consider that Dvārakā, invincible to enemies, over twelve yojanas in size situated in the sea was suitable for the Yadus since it was bigger than Mathurā. His concern was not only for the Yadus. His deep intention was as follows. I have now begun pastimes to rid the world of its burden with the help of the Yadus, because of the people of Vraja who are their relatives. It is not proper that the cowherds whom I take as my relatives should feel crowded by the constantly increasing population of Yadus in Mathurā. Also I worry that the cowherds have fallen into great danger. I have almost allayed their pain of separation from me by my sphūrti of eternal pastimes through Uddhava’s going there. In order that the enemies believe that I am indifferent to the people of Vraja, it is best if I go to a fortress far from here, as part of my human pastimes along with the Yadus in order to protect the cows.