AphDem3.50:13 :ܨܘܡܐ ܕܡܢ ܒܝ̈ܫܬܐ ܟܕ ܢܨܘܡ ܐܢܫ܃ ܡܝܬܪ ܗܘ܂ ܝܬܝܪ ܡܢ ܨܘܡܐ ܕܡܢ ܠܚܡܐ ܘܡܝܐ‏ : when a person fasts avoiding evil things, it is far preferable to fasting from bread and water
See the entire entry for ṣwm vb. to fast