Exodus 15:23

New International Version

When they came to Marah, they could not drink its water because it was bitter. (That is why the place is called Marah.)

Cross References

Numbers 33:8

They left Pi Hahiroth and passed through the sea into the desert, and when they had traveled for three days in the Desert of Etham, they camped at Marah.

Ruth 1:20

“Don’t call me Naomi,” she told them. “Call me Mara, because the Almighty has made my life very bitter.