OS MtSin23:26 :ܕܟܘ ܠܘܩܕܡ ܓܘܗ ܕܟܣܐ ܘܐܦ ܒܪܗ ܕܟܐ ܗܘ‏ : first cleanse the hidden inside and the outside will also be clean
See the entire entry for dky vb. to be clean