john 19:35 And he that saw it bare record, and his record is true: and he knoweth that he saith true, that ye might believe. - Free Bible Online

      35. And he that saw it bare record--hath borne witness.
      and his witness is true, and he knoweth that he saith true, that ye might believe--This solemn way of referring to his own testimony in this matter has no reference to what he says in his Epistle about Christ's "coming by water and blood" (see on 1Jo 5:6), but is intended to call attention both to the fulfilment of Scripture in these particulars, and to the undeniable evidence he was thus furnishing of the reality of Christ's death, and consequently of His resurrection; perhaps also to meet the growing tendency, in the Asiatic churches, to deny the reality of our Lord's body, or that "Jesus Christ is come in the flesh" (1Jo 4:1-3).

JFB.