If I do not (ei ou poiō). Condition of first class, assumed as true, with negative ou, not ei mē = unless.
Believe me not (mē pisteuete moi). Prohibition with mē and the present active imperative. Either “cease believing me” or “do not have the habit of believing me.” Jesus rests his case on his doing the works of “my Father” (tou patros mou), repeating his claims to sonship and deity.