I have many things to say - There are many things which I might say to reprove and expose your pride and hypocrisy. By this he implied that he understood well their character, and that he was able to expose it. This, indeed, he had shown them in his conversations with them.
And to judge of you - To reprove in you. There are many things in you which I might condemn.
But he that sent we is true - Is worthy to be believed, and his declarations about men are to be credited. The meaning of this verse may be thus expressed: “I have indeed many things to say blaming or condemning you. I have already said many such things, and there are many more that I might say; but I speak only those things which God has commanded. I speak not of myself I come to execute his commission, and he is worthy to be heard and feared. Let it not be thought, therefore, that my judgment is rash or harsh. It is such as is commanded by God.”