And the waters divided (Exodus 14:21)
When G-d split the Red Sea, all the waters in the world divided, even the
waters in cisterns and ditches, in jars, cups, casks and bowls... the supernal waters, too, divided...
There was the cloud and darkness, and it illuminated the night (Exodus 14:20)
Can a person who lights a candle say, "So-and-so, who is my friend, may use the light, while so-and-so, who is my enemy, may not"? But G-d's cloud produced light for Israel and darkness for Egypt.
And they could not drink of the waters of Marah, because they were bitter
Because they -- the Children of Israel -- were bitter, everything they tasted
was bitter to them.