John 8:13

Thou bearest record - As if they had said, Dost thou imagine that we shall believe thee, in a matter so important, on thy bare assertion? Had these people attended to the teaching and miracles of Christ, they would have seen that his pretensions to the Messiahship were supported by the most irrefragable testimony.

Thou bearest record of thyself - Thou art a witness for thyself, or in thy own case. See John 5:31. The law required two witnesses in a criminal case, and they alleged that as the only evidence which Jesus had was his own assertion, it could not be entitled to belief.

Is not true - Is not worthy of belief, or is not substantiated by sufficient evidence.

8:13 Thou testifiest of thyself; thy testimony is not valid - They retort upon our Lord his own words, John 5:31; if I testify of myself, my testimony is not valid. He had then added, There is another who testifieth of me. To the same effect he replies here, John 8:14, Though I testify of myself, yet my testimony is valid; for I am inseparably united to the Father. I know - And from firm and certain knowledge proceeds the most unexceptionable testimony: whence I came, and whither I go - To these two heads may be referred all the doctrine concerning Christ. The former is treated of John 8:16, and c, the latter John 8:21, and c. For I know whence I came - That is, For I came from God, both as God and as man. And I know it, though ye do not.