Exodus 14:29

But the sons of Israel walked on the ground in the midst of the sea, and the waters to them were as walls on their right hand and on their left.

And the Children of Israel: The explanation of mentioning this another time is because Pharaoh was drowning while there were still Israelite people crossing. And this was a wonder within a wonder. For in the place that Israel was crossing the Sea, there was an eastern wind drying [the water]; but in the place where Pharaoh and his army were, God brought a different wind to melt the waters that had congealed and became walls. But behold, the two winds were [both] in the Sea and the two places [within it] were close [to each other]. And the testimony for this understanding is that it is written in the Song [of the Sea] (15:8), "With the wind of Your anger, the waters piled up" - and that is the wind that was with Israel; but it is [also] written (15:10), "You made Your wind blow, the sea covered them" - and that is the one that drowned the Egyptians...

ובני ישראל הלכו, all this while the Israelites had already completed crossing the sea while its bed was completely dry.

ובני ישראל הלכו ביבשה, all the while the Egyptians experienced all these problems and were drowning, the Israelites had been walking trough the sea as if it were dry land. The areas still being traversed by Israelites were not affected by the sea reverting to its originals state.

והמים להם חומה, “and the waters were like a wall for them.” The word חמה, wall, is usually spelled with the letterו after the first letter. Here this letter is missing. The reason is that at first the same waters had been a terrible threat חימה, for them until the angel Gavriel came and made the waters pile up as if frozen solid, forming a wall of ice. The angel informed the waters on their right that the Israelites would shortly accept the Torah. Seeing that the Torah had always been on the right side of the Almighty, as we know from Deuteronomy 33,2: אש דת למו, “the fire of the law at His right hand,” this served as a warning to the waters. The angel then turned to the waters on the left side of the Israelites, warning the waters that the Israelites were going to wear phylacteries on their left arms. He also warned the waters behind the Israelites that these would be draped in garments equipped with fringes. When the waters heard all this they turned into solid walls. They divided themselves into 12 lanes. There were walls of frozen water between the 12 tribes so that one tribe could see members of any other tribe through windows in those walls. This enabled members of one tribe to keep in touch with members of the adjoining tribe. This is based on the line: “the waters became a wall for them.” (Yalkut Shimoni section one 247 and 234) According to this Midrash, it would appear that when putting on one’s Tallit, prayer shawl one should throw the tzitzit, fringes, backwards over one’s shoulder. Our author feels that there is no need to do this. He feels that when enveloping oneself in the tallit, the fringes will be thrown backwards as part of that process. How else could the process be called “enveloping oneself?”