If I bear witness of myself. — This verse is the link between the thoughts of Christ’s person (John 5:17-30) and the witness to Him (John 5:32-40). He can do nothing of Himself (John 5:30), and does not even bear witness of Himself. If He did, it would be on technical grounds not to be credited. He meets the objection then doubtless in their minds, and soon expressed in their words. (Comp. Notes on John 8:13-18.)
Related Commentaries of John 5:31
John 5:31
31 If I bear witness of myself, my witness is not true.