Charles Ellicott Commentary John 19:35

"And he that hath seen hath borne witness, and his witness is true: and he knoweth that he saith true, that ye also may believe." — John 19:35 (ASV)

And he that saw it bare record, and his record is true.—(). It may be better to translate the word here, as elsewhere, as “witness,” so that we may grasp the full force of its frequent recurrence. The writer speaks of himself in the third person (compare to Introduction, p. 375), emphasizing the especially important fact that it was an eyewitness—“he that saw it”—who testified to the fact, and one who therefore knew it to be true.

The word translated “true” in this clause is the emphatic word for “ideally true,” which is familiar to the readers of this Gospel. (Compare to Note on John 1:9.) It corresponds to the idea of what evidence should be, because it is the evidence of one who himself saw what he witnesses.

And he knoweth that he saith true, that ye might believe.—The witness was ideally true, and therefore the things witnessed were actually true. He cannot doubt this, and he testifies to it so that others may find in these truths a basis for, and the confirmation of, their faith.