Hebrews 7:28

7:28 For the law appoints as high priests men subject to weakness, ¹  but the word of solemn affirmation that came after the law appoints a son made perfect forever.

Hebrews 9:9

9:9 This was a symbol for the time then present, when gifts and sacrifices were offered that could not perfect the conscience of the worshiper.

[7:28]  ¹ sn See Heb 5:2 where this concept was introduced.