Jewish tradition says that the splitting of the Red Sea was the greatest miracle ever performed. It was so extraordinary that on that day even a common servant beheld more than all the miracles beheld by Isaiah, Jeremiah, and Ezekiel combined. And yet we have one midrash that mentions two Israelites, Reuven and Shimon, who had a different experience.
Apparently the bottom of the sea, though safe to walk on, was not completely dry but a little muddy, like a beach at low tide. Reuven stepped into it and curled his lip. “What is this muck?”
Shimon scowled, “There’s mud all over the place!”
“This is just like the slime pits of Egypt!” replied Reuven. “What’s the difference?” complained Shimon. “Mud here, mud there; it’s all the same.”
And so it went for the two of them, grumbling all the way across the bottom of the sea. And, because they never once looked up, they never understood why on the distant shore everyone else was singing songs of praise. For Reuven and Shimon the miracle never happened.
Lawrence Kushner, God Was In This Place and I, I Did Not Know, p. 26,27