ChronEdess 3:3 :ܘܒܩܝܛܐ ܢܚܬ ܗܘܐ ܠܗ ܠܐܦܕܢܐ ܚܕܬܐ ܕܐܬܒܢܝ ܗܘܐ ܠܗ ܥܠ ܪܝܫ ܡܒܘܥܐ‏ : while in the summer he would go down to the new palace that had been built for him on the source of the spring
See the entire entry for rēš mabbūˁ, rēš mabbūˁā n.m. source of a spring