Rashi on Numbers 33:18/רש"י על במדבר ל״ג:י״ח

1ויחנו ברתמה AND THEY ENCAMPED IN RITHMAH — It was so called with reference to the slanderous speech of the spies, uttered there, as it is said, (Psalms 120:3-4): “What shall be given unto thee, and what shall be done more unto thee, thou deceitful tongue? Sharp arrows of the mighty with coals of juniper (רְתָמִים).