DICT.TW Dictionary Taiwan

 Marah
    bitterness, a fountain at the sixth station of the Israelites
    (Ex. 15:23, 24; Num. 33:8) whose waters were so bitter that they
    could not drink them. On this account they murmured against
    Moses, who, under divine direction, cast into the fountain "a
    certain tree" which took away its bitterness, so that the people
    drank of it. This was probably the 'Ain Hawarah, where there are
    still several springs of water that are very "bitter," distant
    some 47 miles from 'Ayun Mousa.