The first occurrence of I is emphatic, just as you is emphatic in the preceding verse.

It is not that I must have a man’s witness is more literally “Not that the testimony which I receive is from man” (Revised Standard Version). This statement is rendered by Jerusalem Bible “not that I depend on human testimony”; New English Bible has “Not that I rely on human testimony.” The force of Jesus’ words in this context is not to deny the truth of John’s testimony, but rather to affirm that he himself does not need the testimony of any human being. In some languages one may render this clause “I really do not need other people’s words in order to prove who I am” or “It is really not necessary that people say what they know about me.”

I say this only in order that you may be saved. This refers back to verse 33, not to the first half of verse 34. Salvation comes through believing in Jesus. Thus it is legitimate to appeal to John the Baptist, since his witness may teach people to believe. In order to make this clear it may be appropriate to say “I mention John’s testimony only in order that you may be saved.”

If the passive may be saved must be transformed into an active form, then “God” must be made the agent, for example, “in order that God may save you.”

Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on the Gospel of John. (UBS Handbook Series). New York: UBS, 1980. For this and other handbooks for translators see here .