Apostolius 7.99, etc.; see further, n. 1 below.
For 'ultimate evils', e)/sxata kaka/, cf. epsilon 3249. In the present context, however, the proverbial heart of the headword phrase is e)/sxata e)sxa/twn kaka/, 'evils ultimate of ultimates' (deriving from Sophocles, Philoctetes 65) -- evils that can be either inflicted, as here, or suffered. For the former cf. Aelius Aristides, In response to Plato on behalf of the four [prominent Athenians he had censured] 196.13 Jebb (e)/sxata e)sxa/twn pra/ttontas), which generated scholiastic comment. For the latter see Procopius, On the wars of Justinian 8.14.13 (e)/sxata e)sxa/twn kaka\ pa/sxousi).
[1] (Deinias and Kunton, if they are real, are unidentifiable.) The similarity noted between these two phrases and the headword one happens to be one of substance, but the verbal alliteration may nonetheless be what has prompted the comparison; in the Proverbs of the Alexandrians attributed to Plutarch, the present proverb is cited under the one the Suda gives as alpha 123 (q.v.).