John 8:26

I have many things to speak and to judge concerning you

(πολλα εχω περ υμων λαλειν κα κρινειν). Instead of further talk about his own claims (already plain enough) Jesus turns to speak and to judge concerning them and their attitude towards him (cf. verse John 8:16). Whatever they think of Jesus the Father who sent him is true (αληθης). They cannot evade responsibility for the message heard. So Jesus goes on speaking it from the Father.