In Le Morte d'Arthur, what instruction does Arthur give his men before he leaves to meet Mordred?

King Arthur tells his knights never to do anything outrageous nor to commit murder, and always to avoid treason.  He instructs the knights to not be cruel, but merciful to those who ask for mercy; the knights are to preserve chivalry by aiding damsels in distress.  No man should do battle in a wrongful quarrel against the law or for world's good.