And around this matter revolve all the events and occurrences of the splitting of the sea in all its stages. Therefore, the splitting of the sea happened gradually, as the children of Israel passed through it, and not all at once. This way, the danger was close to Israel, like a hair's breadth, throughout the entire time – in order to test Israel and examine their trust in a challenging and difficult trial. With every step they took in the sea until they reached the other side, they had to continually strengthen their absolute trust that it would continue to split before them with each step.

And for this reason, according to Reish Lakish, the Holy One, blessed be He, locked them in with the Egyptians in the sea, surrounded by water on all four sides, so that they were compelled to stretch out their hand and be saved from the sea – in order to test their measure of trust to the utmost, to see whether they would despair upon seeing that they were trapped with no way out, or cast their burden on Hashem and trust in Him completely, and then He would save them.

And for this reason, there was also an emphasis on the casting of the staff in the splitting of the Sea of Reeds specifically, in this miracle, whose entire purpose is the acquisition, deepening, rooting, and spreading of the measure of trust. It was necessary to show the Egyptians that it was not the staff that struck them, but the word of Hashem in the hand of Moshe His servant, which was not as necessary until now in the other plagues.