The reflexive pronoun "himself" emphasizes that it is the Father, not someone less important, who has testified. (See: [[rc://en/ta/man/translate/figs-rpronouns]])
This is an important title for God. (See: [[rc://en/ta/man/translate/guidelines-sonofgodprinciples]])
# the very works that I do, testify about me
Here Jesus says that the miracles "testify" or "tell the people" about him. AT: "What I do shows the people that God has sent me" (See: [[rc://en/ta/man/translate/figs-personification]])
# You do not have his word ... in you, for you are not believing in the one whom he has sent
"You do not believe in the one he has sent. That is how I know that you do not have his word remaining in you"