And the matters have already been explained by Rabbeinu Bachya (Shemot 6:6), as follows: The matter of the splitting of the Red Sea, this is what he said: "And I will redeem you with an outstretched arm and with great judgments." This is a hint to the splitting of the Red Sea, for at that time they were considered redeemed, because a slave who leaves the hand of a harsh master who embittered his life with various kinds of servitude, and was forced to release him and make him a free man against his will, the slave still fears and is afraid that his master will pursue him. The redemption is not complete for the slave until it is clarified by the death of the master. This is why you do not find the term "redemption" in the exodus from Egypt until after the destruction of the Egyptians, as it is said (Shemot 14:27): "And Hashem shook off the Egyptians in the midst of the sea," and immediately following it (14:30): "And Hashem saved Israel that day," for then they were considered redeemed and saved, and then the salvation was complete. End of quote.