In plain words
The Rājasūya yāga. This is not one that everyone may do. Dharmarāja resolved that he would perform this Rājasūya yāga. Kṛṣṇa came to know of this. At once Kṛṣṇa came: "Bāvā, this is not one for you to do. You have no right to do it," He told him firmly. "What is the reason? There are still some kings mightier than you. Śiśupāla, Dantavaktra and Jarāsandha. While you keep kings of such great strength in the kingdom, you have no right whatever to perform the Rājasūya yāga," He said. "If you have set your mind on performing this Rājasūya yāga, conquer these three. Then alone will you become one who holds sole sovereignty. No other kings greater than you will be left in your kingdom. Then alone are you fit to perform this Rājasūya yāga," He taught him; He had the war waged, had the wicked slain, and after that had this Rājasūya yāga performed. That is precisely why, for any yajña however small, for a yāga, even for tasks, one must have certain qualifications.
Now, this Yajurveda has two kinds of saṃskāra. One is called the Brahma-saṃskāra, the other the Āditya-saṃskāra. What is this Brahma-saṃskāra? The one who divided the Vedas and proclaimed them to the world is Vyāsa. His chief disciple was Vaiśampāyana. He was one who had learnt from Vyāsa many kinds of śāstras, the Vedas and their secrets too. Yājñavalkya came to him. Yājñavalkya was one who had a great power of intellect. He was one ready even to offer up his very life for these Vedas. The moment Vaiśampāyana saw this Yājñavalkya, with a joy he could not contain, … He drew him close, cherished him like his own child, brought him up, and went on teaching him all the secrets in the Veda.
But usually every man has some old saṃskāras. He has saṃskāras that are foul. These saṃskāras entered Yājñavalkya too. After he had studied the Vedas and come to know every secret too, after some time had passed, some Ahaṅkāra began. Precisely because this began, the feeling for the guru went on dwindling, step by step. In some matters, some differences of opinion went on arising between the guru and the disciple. Step by step he took to arguing. Vaiśampāyana, who saw this, said: "My son, enough, enough! With today the debt between you and me is settled. As long as there was some bond of Prema between us, I cherished you in so many ways. I looked on you as my own son. I told you secrets I have told no one. There is no use any more in your staying with me. So give back to me the learning I gave you, and go away," he told him. This young man too was one with a will of his own, so he vomited the Veda that had been given him and went away.