成唯識論述記 1.247

1.247

述曰：此以常住難非舒、卷。舒、卷者，盈縮不定之義。量云：汝所執我，應無舒、卷；計常住故；如太虛空。

The Commentary states: This uses permanence to challenge the impossibility of expanding and contracting. 'Expanding and contracting' means the sense of fluctuating expansion and shrinking. The inference is: The self posited by you should be without expansion and contraction; because it is posited to be permanent; like great space.