פּירוש אויף שמות 14:5

ויגד למלך מצרים AND IT WAS TOLD THE KING OF EGYPT — He sent public officers with them, and as soon as they had reached the three days’ journey which he had fixed for them to go and return, and these perceived that they were not going back to Egypt, they came and told Pharaoh on the fourth day (cf. Mekhilta). On the fifth and sixth they pursued after them: on the night of the seventh day they went down into the sea and on the following morning they (the Israelites) sang the Song of Praise and this was the seventh day of Passover. And that is why we read “The Song” (Exodus 15:1 ff.) as the Scriptural lesson on the seventh day of the Festival (Megillah 31a; Seder Olam 5; cf. Sotah 12b).

ויגד למלך מצרים, meanwhile the King of Egypt had received information, etc.” according to Rashi, he had received this information from the spies that he had sent along with the Israelites when they were leaving Ramses. They reported that after three days had passed the Israelites had not made any move indicating that they would return. According to Rashi, on the first day the Israelites had marched only a distance of a single day from Ramses to Sukkot. On the next day they had marched from Sukkot to Eytam, and on the third day they had turned around, so that by that time they were only a day’s march away from the Egyptian border. All this is based on the words: “they turned around and they encamped.” According to Rashi, then, they had presented offerings to G-d while facing Egypt all day long on the third day. The spies reported that on the following day that they had not made any move in the direction of Egypt. This they interpreted as proof that they intended to flee. According to this, the Israelites remained stationary until Pharaoh caught up with them. This is based on the Torah writing that Pharaoh caught up with them while they were along the sea. (verse 9) According to this, the Egyptians engaged in pursuing them on the fifth and sixth day, even though the people had not moved further away at all. We would have to explain this by assuming that an army which travels with chariots, etc., as described, moves more slowly than an ordinary army or cavalry. Otherwise, it makes no sense that they did not face their adversary until the sixth or seventh day.

AND IT WAS TOLD THE KING OF EGYPT THAT THE PEOPLE HAD FLED. “He sent guards with them, and as soon as they had reached the three days’ journey that was fixed for them to go and return, and [these guards] saw that they were not returning to Egypt, they went and reported to Pharaoh on the fourth day. On the fifth and sixth days, the Egyptians pursued after them. On the night of the seventh day, they went down into the sea, and on the following morning, the Israelites uttered the Song, and this was the seventh day of Passover. It is for this reason that [during the Synagogue service] on the seventh day of Passover, we read [the Scriptural portion containing] the Song at the Red Sea.” This is the language of Rashi. And so it is also explained in the Mechilta.²⁷Mechilta here on Verse 3. Ramban’s intent is that the Mechilta states the order of events as mentioned by Rashi. The established custom of reading during the Synagogue service on the seventh day of Passover the Scriptural portion containing the Song at the Red Sea is of later origin, as is evidenced by the fact that in the Mishnah (Megillah 30b) and in Tractate Sofrim (17:5) another reading is indicated. The reading is mentioned in the Gemara of Tractate Megillah 31 a, quoting a Beraitha. The reason why Rashi at this point mentioned the Synagogue custom for the reading of the Torah on the seventh day of Passover, was to show that it is in keeping with “the event of the day.”
In line with the plain meaning of Scripture, the verse here is to be understood in the light of that which G-d said, And Pharaoh will say of the children of Israel: They are entangled in the land.²⁸Verse 3. When the children of Israel [indicated that this was] so, and they turned back and encamped before Phi-hahiroth before Baal-zephon,²⁹Verse 2. this was reported to the king of Egypt. He said that the people were fled and entangled in the desert, and that they were not going towards a definite place to offer sacrifices for G-d. And this is the intent of the verse, and the children of Israel went out with a high hand.³⁰Verse 8. This means that they made themselves a flag and a banner for display, and they went out with mirth and with songs, with tabret and with harp,³¹Genesis 31:27. like people who are redeemed from bondage to freedom, and not like slaves who expect to return to their servitude. All this was told to Pharaoh.