大般涅槃經義記 4.219

4.219

初中「長者」喻佛如來，「若長者子」喻大菩薩已證性者，「多有諸牛」喻三乘眾生，三乘相異名「種種色」。「付一牧人」委行化者，「守護將養」令其攝化。

In the first [line], "the elder" is an analogy for the Buddha, the Tathāgata; "or the elder's son" is an analogy for great bodhisattvas who have already realized the nature; "having many cows" is an analogy for sentient beings of the three vehicles, the different marks of the three vehicles being called "various colors." "Entrusting them to a single cowherd" refers to entrusting them to one who carries out transformation; "guarding and nurturing them" causes him to gather and transform them.