Exodus 15:23

And they came to Marah, and they were not able to drink water from Marah because it was bitter. Therefore {it was named} Marah.

Numbers 33:8

They set out from Pi-Hahiroth and went through the midst of the sea into the desert; and they went a journey of three days into the desert of Etham and camped at Marah.

Ruth 1:20

And she said to them, "You should not call me Naomi; call me Mara, for Shaddai has {caused me to be very bitter}.

Treasury of Scripture Knowledge

Summary

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.

Bible References

Marah

Numbers 33:8
They set out from Pi-Hahiroth and went through the midst of the sea into the desert; and they went a journey of three days into the desert of Etham and camped at Marah.
Ruth 1:20
And she said to them, "You should not call me Naomi; call me Mara, for Shaddai has {caused me to be very bitter}.