Book IX - Chapter XLII - How Sir Tristram took with him the shield, and also how he slew the paramour of Morgan le Fay.
SO then Sir Tristram took his leave of the queen, and took the shield with him. Then came the knight that held Queen Morgan le Fay, his name was Sir Hemison, and he made him ready to follow Sir Tristram. Fair friend, said Morgan, ride not after that knight, for ye shall not win no worship of him. Fie on him, coward, said Sir Hemison, for I wist never good knight come out of Cornwall but if it were Sir Tristram de Liones. What an that be he? said she. Nay, nay, said he, he is with La Beale Isoud, and this is but a daffish knight. Alas, my fair friend, ye shall find him the best knight that ever ye met withal, for I know him better than ye do. For your sake, said Sir Hemison, I shall slay him. Ah, fair friend, said the queen, me repenteth that ye will follow that knight, for I fear me sore of your again coming. With this this knight rode his way wood wroth, and he rode after Sir Tristram as fast as he had been chased with knights. When Sir Tristram heard a knight come after him so fast he returned about, and saw a knight coming against him. And when he came nigh to Sir Tristram he cried on high: Sir knight, keep thee from me. Then they rushed together as it had been thunder, and Sir Hemison brised his spear upon Sir Tristram, but his harness was so good that he might not hurt him. And Sir Tristram smote him harder, and bare him through the body, and he fell over his horse's croup. Then Sir Tristram turned to have done more with his sword, but he saw so much blood go from him that him seemed he was likely to die, and so he departed from him and came to a fair manor to an old knight, and there Sir Tristram lodged.