Cicero, Pro P. Oppio (= Quintilian: Institutiones V 13, 17):

Die Ende 70/Anfang 69 v.u.Z. gehaltene Rede ist nur in fragmentarischer Überlieferung erhalten. Der Vorgang bezieht sich auf Ereignisse im bithynisch-pontischen Krieg des Jahres 74 unter dem Consul M. Aurelius Cotta.

Sed tamen interim oratoris est efficere ut quidem aut contrarium esse aut a causa diversum aut incredibile aut supervacuum aut nostrae potius causa videatur esse coniunctum. Obicitur Oppio quod de militum cibariis detraxerit: asperum crimen, sed id contrarium ostendit Cicero, quia idem accusatores obiecerint Oppio quod is voluerit exercitum largiendo corrumpere.

But sometimes it is the orator’s task to make an argument seem either self-contradictory or irrelevant to the case or incredible or redundant or aiding our case instead. Oppius was accused of stealing from the soldier’s rations, a difficult charge, but Cicero shows that it is self-contradictory, since the same prosecutors accused Oppius of wanting to corrupt the army by largesse.

[Marcus Tullius Cicero, Fragmentary Speeches. Ed. by Jane W. Crawford & Andrew R. Dyck. Cambridge (Mass.)/London 2024, pp. 22 sq.]