Exodus 15:23

A Conservative Version

And when they came to Marah, they could not drink of the waters of Marah, for they were bitter. Therefore the name of it was called Marah.

Cross References

Ruth 1:20

And she said to them, Call me not Naomi. Call me Mara, for the Almighty has dealt very bitterly with me.

Numbers 33:8

And they journeyed from before Hahiroth, and passed through the midst of the sea into the wilderness. And they went three days' journey in the wilderness of Etham, and encamped in Marah.