成唯識論述記 7.311

7.311

論：修習此定至畢竟不退。

[Treatise:] In cultivating this concentration [there are three grades: for the lower grade, having retrogressed, it can manifest again; for the middle grade, it does not necessarily retrogress, but if it retrogresses it cannot manifest again; for the upper grade, it ultimately does not retrogress].