IshEz 51(1) :ܐܢܫ̈ܝܢ ܠܗܠܝܢ ܬܪܝܢܘܬ ܟܝ̈ܢܐ ܕܒܡܫܝܚܐ ܡܦܫܩܝܢ‏ : some interpret these (the silver+gold of electrum) as reference to that dual nature of the Messiah
See the entire entry for trayyānū, trayyānūṯā n.f. duality