They came to Marah, but they could not drink the water from Marah, for it was bitter; that is why it was named “Marah” (“bitter”).
Exodus 14:23
The words “for it was bitter” literally mean, “for they were bitter.” This may be understood to mean that the people, rather than the water, were bitter. In this context, the whole phrase reads, “they could not drink the water from marah for they were bitter.”
When we are bitter, everything tastes bitter. Only when we ourselves are “sweetened” with the positive attitude fostered by Divine consciousness can the water – as well as everything else in life – begin to taste sweet as well.
--Daily Wisdom Volume 3