וַיֹּ֤אמֶר יְהוָה֙ אֶל־מֹשֶׁ֔ה נְטֵ֥ה אֶת־יָדְךָ֖ עַל־הַיָּ֑ם וְיָשֻׁ֤בוּ הַמַּ֙יִם֙ עַל־מִצְרַ֔יִם עַל־רִכְבּ֖וֹ וְעַל־פָּרָשָֽׁיו׃
Sinabi ng Walang-Hanggan kay Moises: “Iunat mo ang iyong kamay sa ibabaw ng dagat, upang bumalik ang tubig sa mga taga-Egipto, sa kanilang mga karwahe at sa kanilang mga mangangabayo.”
Rashi
וישבו המים means THE WATERS that were standing erect as a wall SHALL RETURN to their places and form a cover over the Egyptians.
Or HaChaim
נטה את ידך..וישובו המים, "Incline your hand so that the waters may come back, etc." Why was it necessary for Moses to incline his hand in order to make the waters come back? Surely, the division of the waters was only for the time it took for the Israelites to cross? G'd had not revised the laws of nature permanently! In fact Shemot Rabbah 22 states that when the last of the Israelites ascended from the sea, the last of the Egyptians entered the sea, implying that the sea would come back by itself.
Rashbam
נטה את ידך, as soon as the last Israelite had completed crossing to the far shore of the Sea of Reeds.