Ps-Clem Recogs 2.150:29 :ܘܠܐ ܕܝܢ ܫܪܝܪ ܡܛܠ ܕܠܐ ܝܕܥ ܕܡܢܐ ܐܝܬܘܗܝ ܗ݀ܘ ܡܕܡ ܕܡܗܝܡܢ‏ : and he is not a real believer because he does not know what it is that he believes
See the entire entry for šarrīr adj. firm, true