There are a few proverbs quoted in the novel but only one that lends encouragement to Adam.
This proverb is "Whom God will help, no man can harm." The wise saying is located in the chapter called "News of Roger." In this chapter, Adam is looking for his father, Roger. Cold and hungry, he is discouraged that he has yet to find Roger and Nick, his dog.
To buoy his spirits, Adam begins relating to himself the story of Havelok, the prince of Denmark. In the story, Havelok and his sisters have been imprisoned in a tower by Earl Godard. The evil earl plans to appropriate the children's lands for his own. Bereft of their father, the king of Denmark, the children are powerless to protect themselves. Meanwhile, Godard hires Grim, a fisherman, to drown Havelok. However, Grim gets a surprise when he attempts to do so. The sack that encases Havelok's body begins to glow prior to Grim finishing up his terrible task.
The eerie light convinces Grim that Havelok is the true lord of Denmark. The poor fisherman vows that he will care for Havelok until he is old enough to ride a horse. He also promises to feed Havelok with "milk and bread and cheese and custard pastries." Grim ends his monologue with the saying "Whom God will help, no man can harm." This saying so encourages Adam that he is inspired to continue his search for Roger and Nick.