Musar על שמות 13:17

כי אמר אלהים פן ינחם העם בראותם מלחמה ושבו מצרימה. We can learn from here to what length a person has to go to make "fences," artificial safeguards to prevent himself from sinning. Even G–d Himself made such a "fence" when He decided to let the Israelites travel via an indirect route so as to preclude the people from having second thoughts and wanting to return to Egypt.