Book II - Chapter VIII - How Merlin prophesied that two the best knights of the world should fight there, which were Sir Lancelot and Sir Tristram.
THE meanwhile as this was a-doing, in came Merlin to King Mark, and seeing all his doing, said, Here shall be in this same place the greatest battle betwixt two knights that was or ever shall be, and the truest lovers, and yet none of them shall slay other. And there Merlin wrote their names upon the tomb with letters of gold that should fight in that place, whose names were Launcelot de Lake, and Tristram. Thou art a marvellous man, said King Mark unto Merlin, that speakest of such marvels, thou art a boistous man and an unlikely to tell of such deeds. What is thy name? said King Mark. At this time, said Merlin, I will not tell, but at that time when Sir Tristram is taken with his sovereign lady, then ye shall hear and know my name, and at that time ye shall hear tidings that shall not please you. Then said Merlin to Balin, Thou hast done thyself great hurt, because that thou savest not this lady that slew herself, that might have saved her an thou wouldest. By the faith of my body, said Balin, I might not save her, for she slew herself suddenly. Me repenteth, said Merlin; because of the death of that lady thou shalt strike a stroke most dolorous that ever man struck, except the stroke of our Lord, for thou shalt hurt the truest knight and the man of most worship that now liveth, and through that stroke three kingdoms shall be in great poverty, misery and wretchedness twelve years, and the knight shall not be whole of that wound for many years. Then Merlin took his leave of Balin. And Balin said, If I wist it were sooth that ye say I should do such a perilous deed as that, I would slay myself to make thee a liar. Therewith Merlin vanished away suddenly. And then Balan and his brother took their leave of King Mark. First, said the king, tell me your name. Sir, said Balan, ye may see he beareth two swords, thereby ye may call him the Knight with the Two Swords. And so departed King Mark unto Camelot to King Arthur, and Balin took the way toward King Rience; and as they rode together they met with Merlin disguised, but they knew him not. Whither ride you? said Merlin. We have little to do, said the two knights, to tell thee. But what is thy name? said Balin. At this time, said Merlin, I will not tell it thee. It is evil seen, said the knights, that thou art a true man that thou wilt not tell thy name. As for that, said Merlin, be it as it be may, I can tell you wherefore ye ride this way, for to meet King Rience; but it will not avail you without ye have my counsel. Ah! said Balin, ye are Merlin; we will be ruled by your counsel. Come on, said Merlin, ye shall have great worship, and look that ye do knightly, for ye shall have great need. As for that, said Balin, dread you not, we will do what we may.