IshGen 130:17 :ܫܝܡ ܕܝܢ ܐܬܬܣܝܡ ܒܘܟܪܐ܃ ܡܛܠ ܒܝܬܝܘܬܗ ܕܠܘܬ ܐܠܗܐ‏ : for Shem was placed as eldest because of his close relationship with God
See the entire entry for baytāyū, baytāyūṯā n.f. friendship