Sforno on Exodus 13:17/ספורנו על שמות י״ג:י״ז

1ויהי בשלח...ולא נחם אלוקים דרך ארץ פלשתים, even though it had been G’d’s plan to lead the Israelites to Mount Sinai to receive the Torah there, and only from there to the land of Israel, as He stated Himself in Exodus 6,7-8 :”I will take you as My people, and I will bring you to the land, etc.,” at this point, G’d’s plan was to lead them to the Sea of Reeds, which was neither the route to the land of the Philistines, nor the route that led to Mount Sinai. [we must remember that Moses had stood at Chorev=Mt Sinai at the burning bush and he did not have to cross the sea to do this. Ed.] The major reason for this was to bring about the drowning of Pharaoh and his army in the sea. [it is important to always remember that due to man’s free will, G’d cannot deal with man in the way He deals with inert objects or even animals, none of which could oppose Him. G’d needs to create a scenario which gives man a chance to delude himself, thus bringing him to act in a manner enabling G’d to insure that His design will be carried out. Ed.] An example of G’d acting in this manner is described in Judges 4,7 where G’d Himself speaks about how He “dragged” Sisera and his army and 900 armoured vehicles across the river Kishon to face Barak. The simplest route to get to the Sea of Reeds was by traversing the land of the Philistines. דרך ארץ פלשתים, G’d did not want them to travel this route

2 כי קרוב הוא because this route was too close to Egypt, afforded too easy a way to return to Egypt. Also, seeing it was a much traveled route, too many travelers would be able to report to Pharaoh about the Israelites and also too many Egyptians could keep the Israelites informed of what transpired in their country. If the Israelites would have to face combat

3בראותם מלחמה, when they would hear that the Egyptians were mobilizing for war preparatory to chasing after the Israelites, the latter would no doubt return to Egypt out of fear of being killed. This is why G’d decided to lead them on a route not frequented by travelers at all.