Acts 26:26

λανθάνειν γὰρ αὐτόν τι τούτων οὐ πείθομαι οὐδέν, for I am persuaded that none of these things is hidden from him, i.e. none of the history of the life and works of Jesus, of His death and resurrection, of the marvellous gifts of Pentecost, and the preaching of the Gospel since Jesus had been crucified.

The grammar presents some anomaly from the occurrence of τι and οὐδὲν in the same sentence. It is perhaps best to take the former adverbially = ‘in any degree.’ Then οὐ before πείθομαι is only the Greek manner of intensifying a negative idea, and need not be noticed in the English idiom.

ἐν γωνίᾳ πεπραγμένον, done in a corner. That there was no lack of knowledge about our Lord among the Jewish people we can be sure from the excitement which during His life He caused by His mighty works, also from the efforts put forth to stop His teaching, efforts which culminated in a trial in which both Jewish and Roman magistrates were consulted, and by the exclamation of the Pharisees (John 12:19) ‘The world is gone after Him,’ and the declaration (Acts 17:6) ‘These that have turned the world upside down.’

Chrysostom says: ἐνταῦθα περὶ τοῦ σταυροῦ λέγει τοῦτο, καὶ περὶ τῆς�, καὶ ὅτι πανταχοῦ τῆς οἰκουμένης γέγονε τὸ δόγμα.