Book III - Chapter XV - How when he was come to Camelot he was sworn upon a book to tell the truth of his quest.

AND therewith they departed, and came there as the head of the lady lay with a fair yellow hair that grieved King Pellinore passingly sore when he looked on it, for much he cast his heart on the visage. And so by noon they came to Camelot; and the king and the queen were passing fain of his coming to the court. And there he was made to swear upon the Four Evangelists, to tell the truth of his quest from the one to the other. Ah! Sir Pellinore, said Queen Guenever, ye were greatly to blame that ye saved not this lady's life. Madam, said Pellinore, ye were greatly to blame an ye would not save your own life an ye might, but, save your pleasure, I was so furious in my quest that I would not abide, and that repenteth me, and shall the days of my life. Truly, said Merlin, ye ought sore to repent it, for that lady was your own daughter begotten on the lady of the Rule, and that knight that was dead was her love, and should have wedded her, and he was a right good knight of a young man, and would have proved a good man, and to this court was he coming, and his name was Sir Miles of the Launds, and a knight came behind him and slew him with a spear, and his name is Loraine le Savage, a false knight and a coward; and she for great sorrow and dole slew herself with his sword, and her name was Eleine. And because ye would not abide and help her, ye shall see your best friend fail you when ye be in the greatest distress that ever ye were or shall be. And that penance God hath ordained you for that deed, that he that ye shall most trust to of any man alive, he shall leave you there ye shall be slain. Me forthinketh, said King Pellinore, that this shall me betide, but God may fordo well destiny.

Thus, when the quest was done of the white hart, the which followed Sir Gawaine; and the quest of the brachet, followed of Sir Tor, Pellinore's son; and the quest of the lady that the knight took away, the which King Pellinore at that time followed; then the king stablished all his knights, and them that were of lands not rich he gave them lands, and charged them never to do outrageousity nor murder, and always to flee treason; also, by no means to be cruel, but to give mercy unto him that asketh mercy, upon pain of forfeiture of their worship and lordship of King Arthur for evermore; and always to do ladies, damosels, and gentlewomen succour, upon pain of death. Also, that no man take no battles in a wrongful quarrel for no law, nor for no world's goods. Unto this were all the knights sworn of the Table Round, both old and young. And every year were they sworn at the high feast of Pentecost.

Explicit the Wedding of King Arthur. Sequitur quartus liber.