Book XXI - Chapter III - How after, Sir Gawaine's ghost appeared to King Arthur, and warned him that he should not fight that day
AND then the king let search all the towns for his knights that were slain, and interred them; and salved them with soft salves that so sore were wounded. Then much people drew unto King Arthur. And then they said that Sir Mordred warred upon King Arthur with wrong. And then King Arthur drew him with his host down by the seaside, westward toward Salisbury; and there was a day assigned betwixt King Arthur and Sir Mordred, that they should meet upon a down beside Salisbury, and not far from the seaside; and this day was assigned on a Monday after Trinity Sunday, whereof King Arthur was passing glad, that he might be avenged upon Sir Mordred. Then Sir Mordred araised much people about London, for they of Kent, Southsex, and Surrey, Estsex, and of Southfolk, and of Northfolk, held the most part with Sir Mordred; and many a full noble knight drew unto Sir Mordred and to the king: but they that loved Sir Launcelot drew unto Sir Mordred.
So upon Trinity Sunday at night, King Arthur dreamed a wonderful dream, and that was this: that him seemed he sat upon a chaflet in a chair, and the chair was fast to a wheel, and thereupon sat King Arthur in the richest cloth of gold that might be made; and the king thought there was under him, far from him, an hideous deep black water, and therein were all manner of serpents, and worms, and wild beasts, foul and horrible; and suddenly the king thought the wheel turned up-so-down, and he fell among the serpents, and every beast took him by a limb; and then the king cried as he lay in his bed and slept: Help. And then knights, squires, and yeomen, awaked the king; and then he was so amazed that he wist not where he was; and then he fell a-slumbering again, not sleeping nor thoroughly waking. So the king seemed verily that there came Sir Gawaine unto him with a number of fair ladies with him. And when King Arthur saw him, then he said: Welcome, my sister's son; I weened thou hadst been dead, and now I see thee alive, much am I beholding unto Almighty Jesu. O fair nephew and my sister's son, what be these ladies that hither be come with you? Sir, said Sir Gawaine, all these be ladies for whom I have foughten when I was man living, and all these are those that I did battle for in righteous quarrel; and God hath given them that grace at their great prayer, because I did battle for them, that they should bring me hither unto you: thus much hath God given me leave, for to warn you of your death; for an ye fight as to-morn with Sir Mordred, as ye both have assigned, doubt ye not ye must be slain, and the most part of your people on both parties. And for the great grace and goodness that almighty Jesu hath unto you, and for pity of you, and many more other good men there shall be slain, God hath sent me to you of his special grace, to give you warning that in no wise ye do battle as to-morn, but that ye take a treaty for a month day; and proffer you largely, so as to-morn to be put in a delay. For within a month shall come Sir Launcelot with all his noble knights, and rescue you worshipfully, and slay Sir Mordred, and all that ever will hold with him. Then Sir Gawaine and all the ladies vanished.
And anon the king called upon his knights, squires, and yeomen, and charged them wightly to fetch his noble lords and wise bishops unto him. And when they were come, the king told them his avision, what Sir Gawaine had told him, and warned him that if he fought on the morn he should be slain. Then the king commanded Sir Lucan the Butler, and his brother Sir Bedivere, with two bishops with them, and charged them in any wise, an they might, Take a treaty for a month day with Sir Mordred, and spare not, proffer him lands and goods as much as ye think best. So then they departed, and came to Sir Mordred, where he had a grim host of an hundred thousand men. And there they entreated Sir Mordred long time; and at the last Sir Mordred was agreed for to have Cornwall and Kent, by Arthur's days: after, all England, after the days of King Arthur.