। ॥ ५६३ ॥
In plain words
'This Self, indeed, is imperishable' - that is what scripture declares, and it declares this exactly by setting the Self apart from everything that does perish, everything that changes.
Close to the Sanskrit
'Verily, O, this Self is imperishable' - thus the scripture declares of the Self its imperishability, [precisely by contrast] among things that perish, the mutable.