In Nathaniel Hawthorne's "Young Goodman Brown," there are several instances that point to Brown's plan to meet with the old gentleman who is actually the devil. (And Brown knows who he is meeting.)
The first bit of foreshadowing comes not from Faith—as he insinutates—but from Brown's words to her. As she begs him not to got out for the evening, and he gently chides her, asking if she does not trust him. She has said nothing to convey any mistrust of her new husband: he presents the topic.
My journey, as thou callest it, forth and back again, must needs be done 'twixt now and sunrise. What, my sweet, pretty wife, dost thou doubt me already, and we but three months married?
There is also foreshadowing in Faith's wish for him, as she sends Brown off on his "errand:"
And may you find all well when you come back.
Later we know that this will not be the case. There is also a sense of foreshadowing as Brown takes leave of his wife, offering words that sound almost like a spell against evil, or a child's prayer:
Say thy prayers, dear Faith, and go to bed at dusk, and no harm will come to thee.
As the young husband departs, he looks back as his wife who wears a sad countenance, and his commentary make one sure that he is doing something that he should not do—he infers that her goodness is such that to know what he is doing would do damage to her. He also makes a promise that after this one night he will do what is right and "follow her to heaven."
Poor little Faith!...What a wretch am I to leave her on such an errand! She talks of dreams, too. Methought as she spoke there was trouble in her face, as if a dream had warned her what work is to be done tonight. But no, no; 'twould kill her to think it. Well, she's a blessed angel on earth; and after this one night I'll cling to her skirts and follow her to heaven.
The setting described as Brown makes his way onward also foreshadows something dark and/or evil ahead, especially in that he has also resolved to be better in the days ahead (inferring he will not be "better" now)—that he has an "evil purpose."
With this excellent resolve for the future, Goodman Brown felt himself justified in making more haste on his present evil purpose. He had taken a dreary road, darkened by all the gloomiest trees of the forest, which barely stood aside to let the narrow path creep through, and closed immediately behind. It was all as lonely as could be...
So the reader gets the sense that Brown believes his wife is pure of heart and he is doing something he should not do. He utters words that sound like a protective spell—or perhaps a prayer. He infers that he will do this "thing" only one time, and never again. Then he walks a "dreary road," enters the woods (where Puritans believed the devil lived) which are dark and gloomy: where any evil could hide itself.
The fact that Brown meets the devil should be no surprise with the many examples of foreshadowing—they prepare the reader that there is some dark purpose to Brown's movements—and a dark person at the end of his "errand" is not unexpected.