There is no Greek equivalent for then in Jesus’ question Why, then, do you question me? However, it is natural to include it in English, since Jesus’ question is based on what he has said in verse 20.

Question the people who heard me. Ask them what I told them is one sentence in Greek: “Ask the people who heard what I said to them.”

In Greek they know what I said begins with the interjection ide, which was discussed at 16.29. It is used for emphasis, and most translators omit it.

Jesus’ argument in verses 20-21 must be understood in the light of contemporary court procedures. According to a later Jewish law, which may have been in force in Jesus’ day, it was improper for an accused person to be asked to testify against himself. Jesus is demanding that the trial be conducted in legal fashion, with proper witnesses.

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 .