成唯識論述記 3.456

3.456

述曰：常者，相續義。無轉者，一類義。我是一、常，故此似我，顯第七識恒緣執我。

The Commentary states: "Constant" means continuous. "Without shifting" means of a single category. The self is single and constant; therefore this resembles a self, showing that the seventh consciousness constantly takes it as an object and grasps it as a self.