מדרש אויף שמות 5:3

"by way of the land of the Philistines, for it was near": Near (i.e., "close") is the thing of which the Holy One Blessed be He spoke to Moses (Exodus 2:12): "When you take the people out of Egypt, you will serve G–d on this mountain." Variantly: "for it was near": It afforded easy return to Egypt, viz. (Ibid. 5:3) "Let us go a three days' distance in the desert." Variantly: "for it was near": Close (in time) was the oath that Abraham had sworn to Avimelech, viz. (Genesis 21:23) "And now, swear to me here by G–d that you will not deal with me falsely (by trespassing on my land), or to my son or my grandson," and his grandson was still alive. Variantly: "for it was near": The first war (that with Egypt) was too close to the second (that with Canaan). Variantly: "for it was near": The Canaanites had only recently acquired the land, and (Genesis 15:16) "And they (the Israelites) shall return here in the fourth generation, for the sin of the Amorites is not yet complete."

Why is it written? It is deliberately superfluous to signal a gezeirah shavah (i.e., "identity"), viz.: It is written here (in Exodus) "Hebrew," and there (in Devarim) "Hebrew." Just as there, "Hebrew" refers to the servant (and not to the master); here, too, "Hebrew" refers to the servant (and not to the master). And though there is no proof for this (i.e., that "servant Hebrew" is to be understood as "a servant who is a Hebrew" (and not as "the servant of a Hebrew"), there is support for it, viz. (Exodus 5:3) "The G–d of the Hebrews revealed Himself to us" — (the G–d) of "Avram the Hebrew" (Genesis 14:13).

And the Lord spoke unto Moses and unto Aaron, and gave them a charge unto the children of Israel, and unto Pharaoh, king of Egypt (ibid., v. 13). By virtue of this verse He made them equals. The Holy One, blessed be He, said to them: Be respectful, and pay homage to the king through whom I desire to execute judgment upon him. Whereupon Moses said to him: Let us go, we pray thee, three days’ journey into the wilderness, and sacrifice unto the Lord our God; lest He fall upon us with pestilence, or with the sword (ibid. 5:3). He said Lest He fall upon us to demonstrate that he was acting respectfully toward the king.