We will read John 8:2-9 (from the NASB) and then offer a few comments. “Early in the morning He came again into the temple, and all the people were coming to Him, and He sat down and began to teach them. The scribes and the Pharisees brought a woman caught in adultery, and having set her in the center of the court, they said to Him, ‘Teacher, this woman has been caught in adultery, in the very act. Now in the Law Moses commanded us to stone such a woman; what then do You say?’ They were saying this, testing Him, so that they might have grounds for accusing Him. But Jesus stooped down and with His finger wrote on the ground. But when they persisted in asking Him, He straightened up, and said to them, ‘He who is without sin among you, let him be the first to throw a stone at her.’ Again He stooped down and wrote on the ground. WHEN THEY HEARD IT, they began to go out one by one, beginning with the older ones, and He was left alone, and the woman.”

For the most part, this account is self-explanatory. We know from verse 6 that the only reason the Pharisees brought this woman to Jesus was to TEST HIM, “that they might have grounds for accusing Him.” They had no real interest in upholding the Law of Moses; their desire was to trap Jesus into doing something that would contradict Scripture. If He said, “Let her go,” He would be contradicting the Law of Moses.” If He said, “Stone her,” He would then be guilty of contradicting the message of grace and forgiveness He had been preaching. Jesus didn’t answer them; He simply stooped down on the ground and began to WRITE; in fact, He did it twice. But it’s what He SAID that had the greatest impact on the self-righteous religionists that stood before Him. When He said, “He who is without sin among you, let him be the first to throw a stone at her first,” their consciences went to work against themselves. Instead of them having something to ACCUSE THE LORD JESUS OF, their consciences ACCUSED THEM! Romans 2:15 speaks of this work of the conscience in the sinner, “Who show the work of the law written in their hearts, THEIR CONSCIENCE ALSO BEARING WITNESS, and between themselves THEIR THOUGHTS ACCUSING or else excusing them.” In their case the moment Jesus brought up the thought of sin in their own lives, their conscience ACCUSED THEM (of the many sins they had committed) and their guilt caused them to leave the Lord’s holy presence.

As to your question, we are NOT told what He wrote and we have no way of knowing. Some believe He was writing out the Ten Commandments, just as God had written the Ten Commandments twice with His finger on Mt. Sinai (see Exodus 31:18 and 34:1). This is possible, but again we aren’t told so it would be mere speculation to offer a guess. As to WHY He wrote on the ground, I feel quite sure it was meant for their eyes and more than likely they did see exactly what He wrote. Was it indeed a list of the Ten Commandments or perhaps a list of various sins they were guilty of? He no doubt wrote what He wrote to convict them, but I would emphasize again that it was what they HEARD rather then what they SAW that brought real conviction to their consciences and caused them to retreat from Jesus’ holy presence. (323.1) (DO)