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.
Numbers 33:8 And they departed from before Pihahiroth, and passed through the middle of the sea into the wilderness...
marah. i.e. bitterness
Ruth 1:20 And she said to them, Call me not Naomi, call me Mara: for the Almighty has dealt very bitterly with me.