Ye despisers (hoi kataphronētai). Not in the Hebrew, but in the lxx. It is pertinent for Paul’s purpose.
Perish (aphanisthēte). Or vanish away. First aorist passive imperative. Added by the lxx to the Hebrew.
If one declare it unto you (ean tis ekdiēgētai humin). Condition of third class with present middle subjunctive, if one keep on outlining (double compound, ek̇di̇ēgeomai) it unto you. Paul has hurled a thunderbolt at the close.