Ἐμοὶ δὲ τοιοῦτον ἔργον ἔστ' εἰργασμένον · such a deed have I accomplished as to stop the mouths of each and every one of my enemies as long as there is anything left of the shields from Pylos (ε 1061) · Suda
Kleon is harking back to the events at Pylos↗ and Sphacteria. It was the custom to dedicate the arms [captured] from wars1 in the temples. So as long, he is saying, as the arms from Pylos↗ and Sphacteria which I dedicated are on show, nobody will dare to speak against me.
Aristophanes, Knights 844-46 (web address 1), with comment from the scholia there. For Kleon see generally kappa 1731. For his military success at Pylos↗ and Sphacteria, in the SW Peloponnese, see generally Thucydides 4.1-41 (web address 2).
1So here; the scholiast has 'enemies' (a difference of one letter in the Greek).