Someone shared with me the following:
ויצעקו בני ישראל, Rashi comments – תפסו אומנות אבותם בידם. They grabbed the practice of their fathers – davening. But Moshe tells them ואתם תחרישון, you should be silent. Why? What were they doing wrong?
In Targum Yonasan, we find an interesting translation. ואתון שתוקו והבו יקרא ותושבחתא ורוממו לאלקכון. Be silent, and offer praises to your G-d. Is singing praises silence? Perhaps Moshe is giving them guidance. He is telling them that praying and asking for something is contraindicated here. Such tefilos require the fitness of the individual. As we know, there are Mal’ochim that are mekatreg, and the situation at the Yam Suf involved kitrug of הללו עובדי עבודה זרה. Moshe Rabbeinu troubleshot this dilemma. If tefilos are expressed as שירות ותשבחות, there isn’t kitrug.
דבר אל בני ישראל ויסעו. The message is that their tefilos of שירות ותשבחות have been accepted already. Now, move.