In chapter 11 what does Kevin explain to Max about quests and a promise?

In chapter 11, Kevin (also known as Freak) explains to Max that "it's okay to break a promise if you're on a quest." He tells him this because Max has promised his grandmother that he won't go to a certain place, called the Testaments, but Kevin and Max have found a purse that belongs to a woman who lives there, and Kevin says that they should go on a quest to return the purse because there might be a reward in it for them.
Kevin imagines that this quest is like a quest that medieval knights might have had to carry out. He imagines that he and Max are like these knights, carrying out a quest to help a damsel in distress (the woman who has lost her purse). He also says that quests involve oaths, which he implies are very important, more important than a promise a boy might make to his grandmother.
When Kevin and Max get to the Testaments, Kevin, upon hearing "screaming noises," suggests to Max that they "should reconsider this particular quest."