The question comes from John 8:2-11:

“Early in the morning he (Jesus) came again to the temple. All the people came to him and he sat down and began to teach them. The scribes and the Pharisees brought a woman who had been caught in adultery; and making her stand before all of them, they said to him, ‘Teacher, this woman was caught in the very act of committing adultery. Now in the law Moses commanded us to stone such women. Now what do you say?’ They said this to test him, so that they might have some charge to bring against him. Jesus bent down and wrote with his finger on the ground. When they kept on questioning him, he straightened up and said to them, ‘Let anyone among you who is without sin be the first to throw a stone at her.’ And once again he bent down and wrote on the ground. When they heard it, they went away, one by one, beginning with the elders; and Jesus was left alone with the woman standing before him. Jesus straightened up and said to her, ‘Woman, where are they? Has no one condemned you?’ She said, ‘No one, sir.’ And Jesus said, ‘Neither do I condemn you. Go your way, and from now on do not sin again.’”

There is considerable controversy regarding the authenticity of the passage. The earliest and most respected ancient manuscripts (Sinaticus and Vaticanus) omit the passage. Numerous Greek manuscripts dating from the 300’s AD onward DO contain the passage. 

The fragment has been discussed and interpreted from the earliest ages of Christian commentary. There is enough debate to safely conclude that Jesus did encounter some situation similar to that outlined in John 8. Jesus used it to teach at least two valuable lessons of good Christian conduct, namely: ‘Do not readily accuse others when you are yourself a sinner’ and ‘repent and sin no more.’

The question of what Jesus wrote on the ground has been debated as much as the authenticity of the passage itself. However, there does seem to be a simple solution. Jesus directly quoted from the Law in Deuteronomy 22:22. It reads, “If a man is found sleeping with another man’s wife, both the man who slept with her and the woman must die. You must purge the evil from Israel.”

Jesus may have begun to write this passage on the ground. As he did so, every Jew would have realized that they had omitted some of the words in that Law. They were too ashamed to admit that while condemning the woman, they had ignored the man’s adulterous sin. These accusing Jews were not following that Law.  Essentially, Jesus could easily have written “WHERE IS THE MAN?”