Syr-RomLaw.16.6 :ܐܢ ܢܙܒܢ ܓܒܪܐ ܥܒ݂ܕܐ ܩܠܐܪܣܐ ܕܡܬܬܪܓܡ ܬܢܘܝ ܫܦܝܪܬܐ‏ : if a man buys a slave under a proper condition, which is translated as a proper agreement
See the entire entry for qlˀrsˀ n.f. proper condition