Then there began between the two of them a battle so great and marvelous that any man who saw it would have
thought them valiant men. The battle lasted in this manner until noon, and then both were exceedingly weary, which was not surprising, for the healthier of the two had four great, deep wounds in his body, and they had lost so much blood that they had to rest to recover strength and breath.

When noon had come, and they were a little rested, Gawain—who was of such a nature that in all seasons his strength doubled around noon and grew and increased more than any other man’s—as soon as noon had come felt himself as light and agile as he had been at the beginning, or more so. He seized his sword and shield at once, ran to where he saw Morholt, and began to give him great blows on the helmet and the shield and everywhere he could reach him, and he treated him so badly in a short time that the other was dumbfounded and said to himself, “By my faith, now I see the greatest marvel I ever yet saw, for I know well that just now I had as good as brought this knight to defeat, and now he is as fresh and recovered as if he had not struck a blow with his sword today! I never yet saw such a marvel.”

Gawain, who wanted only to pursue him and injure him thoroughly, pressed him constantly with his sharp sword so hard that the other knight grew afraid of being shamed in the battle. Nevertheless, he trusted in the fact that he had never, in all his life, found a knight who could endure against him to the end. He still felt light and agile enough, and he had as yet no mortal wound, nor had he lost so much blood that he was weakened by it, so he suffered and endured the blows Gawain threw at him hard and fast and shielded himself the best he could; he knew much of the art of defense, for he had learned it a
long time ago, and he was in no hurry to strike but bore himself very wisely, for he saw that he must, since he knew truly that his opponent was the very best knight he had ever met or would ever hope to meet.

Thus the fight lasted until around nones, and Morholt did little except endure, and then Gawain began to tire somewhat and to strike more slowly than he had before, for invariably the strength that came to him around noon lasted him not quite until nones.

[...]

The battle of the two knights lasted a long time, for both were powerful and agile. When nones had
passed and Gawain was somewhat tired and his arm began to hurt, Morholt, perceiving that, said to him, “Sir knight, it is now late. You are tired, and so am I, and we have so tested each other that we should know each other well. I don’t say it to flatter either you or myself, but I tell you this much, that I don’t think there has been such a fine battle as this one these ten years in Great Britain. Because we have done so much, without either of us being defeated, I now earnestly suggest that we leave it at that, for certainly, continuing could only result in the death of both of us. If you kill me and I you, that will be a great pity, because you may yet come to great honor, God willing, and I, too. Certainly, I suggest this not from any fear or doubt I feel, only because it is my opinion that we cannot do better.”

Post-Vulgate Merlin