Matthew Poole and continuators on John 18:37

37 Pilate therefore said unto him, Art thou a King then ? Jesus answered, Thou sayest that I am a King . To this end was I born, and for this cause came I into the world, that I should bear witness unto the truth . Every one that is of the truth, heareth my voice .

Pilate seems to have spoken this, rather in derision and mockery, than out of any desire to catch him in his words:

Christ neither owneth himself to be a King, nor yet denieth it, but tells Pilate that he said so; and to this end he was born, and for this cause he came into the world, to bear testimony to the truth. i. e. I cannot deny but that I have a Spiritual Kingdom, that is truth, and I must attest the truth;

It was a part of my errand into the World;

and every one who is by Divine grace disposed to believe, and love the truth, will hear and obey my Doctrine.