In John 8:6-8 (KJV) The Scripture said :
6 This they said, tempting him, that they might have to accuse him. But Jesus stooped down, and with his finger wrote on the ground, as though he heard them not. 7 So when they continued asking him, he lifted up himself, and said unto them, He that is without sin among you, let him first cast a stone at her. 8 And again he stooped down, and wrote on the ground.
What did Christ write on the ground?
Although we simply are not told what Jesus "wrote" in this action, there has been informed (?) speculation about it for centuries. We need first to make two quick observations on the Greek:
Since the time there was commentary on this text, there has been speculation about what Jesus wrote, and why. That interest has continued unabated over the centuries, and past decades of scholarly writing are just the same.
There is something that connects this episode, now residing in John 8, with the Decalogue -- an allusion noticed as early as Ambrose, the fourth century bishop of Milan, and has been argued for as recently as 1990, in J.A. Sander's contribution, "'Nor Do I...': A Canonical Reading of the Challenge to Jesus in John 8," in The Conversation Continues: Studies in John and Paul, ed. by R. T. Fortna and B. R. Gaventa (Abingdon, 1990) pp. 337-47.1
But this interesting suggestion takes its place beside the welter of other suggestions accounting for Jesus' actions in this pericope. The most complete and conveniently available catalogue of suggestions (which still stops short of being absolutely comprehensive) is in Raymond Brown's Anchor Bible Commentary.2 Here's the quick run down:
As noted, this is not a comprehensive list: do see the Google Scholar link to explore many other proposals and arguments, should that be of interest.
Notes
Keeping in mind that many manuscripts omit John 8:1-11 altogether, the Nanianus Codex includes the phrase, ενος εκαστου αυτων τας αμαρτιας - "the sins of every one of them" - after "and wrote on the ground ..." in verse 8. The phrase is also included in Miniscule 700 and about a half-dozen other Greek manuscripts as well as in some ancient Armenian manuscripts.
These are not terribly old manuscripts, dating only from 9th century but they either witness an earlier reading that was lost or, more likely, a tradition that had been held in the Church. Another answer to your question has pointed out that Jerome (c. 415, in Against the Pelagians, Bk. II, 17) had this interpretation, even suggesting that Jesus was fulfilling a prophesy by Jeremiah:
Jeremiah 17:13 LXX
O Lord, the hope of Israel, let all that have left thee be ashamed, let them that have revolted be written on the earth, because they have forsaken the fountain of life, the Lord.
To understand what Jesus wrote on the ground we must first understand why Jesus wrote on the ground. The key is to look at the way the Pharisees approach Jesus in verse 5:
Now in the law, Moses commanded us to stone such women. So what do you say?
(i.e. they are assuming Jesus will say something different than Moses) Then verse 6:
"But Jesus...began to write with his finger on the ground"
By this act, Jesus is showing them that it's not Moses who commanded them to stone sinners but He. It is Jesus (being God) who both wrote and gave the law at mount Sinai (Exodus 31:18);
He gave Moses the two... tablets of stone, written by the finger of God
Notice the language similarities, add the probable fact that the ground that Jesus wrote on was stone and the meaning of the passage becomes clear.
Conclusion: I believe Jesus, as he is writing on the ground/stone with his finger is remembering what He did on Mount Sinai while at the same time correcting them: "With this very finger I wrote the law on the stone tablets on Mount Sinai and gave them to Moses my servant. It is not he that commands what should be done with this woman, but I. And the law that I wrote, condemn you just as much as her".
My best guess at what Jesus wrote on the ground is the 10 commandments or maybe just Thou shall not commit adultery.
So in the same manner as Jesus in John 6:32 says:
...it was not Moses who gave you the bread from heaven, but ...My Father
He here says: it was not Moses who gave you the law from heaven but I
One of the interpretations in the ancient Church tradition that He wrote each of the presenter's sins is theologically speaking correct, for He showed His divine feature of knowing hearts - καρδιογνώστης /Acts 1:24/ - (which feature belongs properly only to the Father, the Son (Jesus), who knows Father just as Father knows Him (Matt 11:27), and Holy Spirit who "knows the depth of God" (1 Cor. 2:10) - the epistemological equality of the three, in fact, indicating their ontological equality also), and this is matching with other such occurrences in the Gospels when Jesus shows the same divine feature, like in Luke 5:22, or Mark 2:8, or in the instance with the Samaritan woman whom He astonished by telling her about all her previous husbands and that her present partner was not her lawful husband in John's ch. 4.
Moreover, He also forgives her, for by saying that "neither I condemn you, go and sin no more", he implies that from that instance onwards the previous sin is not accounted to her, thus showing his another divine feature (again, properly belonging only to the Father, the Son and the Holy Spirit) - the sovereign authority of forgiving sins, which ontologically speaking is nothing else but making a healing touch into one's soul's/heart's depth, for sin is nothing but a scar and infirmity of soul. This authority He shewed in other instances as well, for which He was considered to be a blasphemer as making Himself an usurper and appropriator of something belonging properly only to God (cf. Mark 2:7 or Matthew 9:3).
To sum it up, Jesus makes manifest his double divine feature: 1) knowing the depth of human hearts and 2) and His sovereign authority of forgiving sins, that is to say, of penetrating this human depth with a healing touch of His Grace.
With all that it can be said that the tradition of Jesus' writing each of the presenter's sins (probably it is implied the similar sins of adultery for which they were poised to kill the woman) matches well the Gospels' teaching about the divine dignity of Jesus. Thus the tradition is theologically truthful and in accord with other testimonies of the Gospels. However, whether this tradition is objectively true or not, that is to say, whether they really took a look on Jesus' words written on ground and their consciences were pricked already by them before Jesus said also loudly those famous words, is unclear, and John purposefully leaves a riddle for us that we may be free to venture our interpretations and read the text more attentively and creatively, thus, with a greater spiritual benefit to ourselves.
A possible solution
But is it at all possible that Jesus wrote sins of a l l present there with those threatening stones? Hardly! For had He written sins of all of them, it would have taken too much time both for the Writer and the readers. But it is quite possible and plausible that He wrote sins of few most ardent and zealous among them, the very instigators and leaders of the crowd, and as they read their sins, they dropped the stones, the rest following their lead. It is quite logical also from the textual point of view, as a matter of fact, because we read immediately (John 8:9) that first the eldest left the place the rest following after them; thus, it is quite possible that Jesus wrote sins of those few eldest who were also the leaders and instigators, the driving force of the entire affair, and when those few got pricked in their consciences after seeing their sins written down, then they dropped stones and departed, providing thus an example to the rest, without Jesus having any need to write sins also of the latter.
But again, John leaves us riddles to be solved or speculated about, and admirably so, for our own benefit.
Though I have heard sermons and lessons speculating what it could be, we are never told. The verb used in both verse 6 and 8 is grapho which means to write or describe. He wrote on the ground, said whomever is without sin should throw the first stone, then wrote again. We don't know what He wrote, but whatever it was, along with what He said, was convicting enough that the accusers left.
It is not possible to prove that all present in the area, whether a domestic room or a very large place of congregation, could have been able to see what Jesus wrote.
Such crowds, usually, attended him that it is more likely than not that only those in his vicinity could have seen the writing.
In any case, they were convicted by what he said, not by what he wrote.
v9 they which heard . . went out, one by one . . .
He said, 'he that is without sin,' and he wrote on the ground.
What he said convicted them (v9, again).
The combination of the Son of God writing with a finger on the ground and the fact that God himself only ever wrote one thing in history leads to a conclusion that is, to my mind, so convincing that I believe it is inescapable.
It is very likely that many present could only hear his words and see, at a distance, only the fact that he was bent down, writing on the ground.
And his words were so convicting, that they were too ashamed to stay in the building.
Who was among them who had never sinned against the writing that God, himself, had written ?
Not a single one of them.
Hath no man condemned thee ? No man, Lord.
Jesus was in the temple, or in its close vicinity. The ground was made of stone. He could therefore not have managed to make an imprint on the ground, as he would have been able to do if the ground was made of sand, or soil. When writing on the ground he would, therefore, have had to trace the words over and over again. What he repeatedly traced with his finger must, therefore, have been something short. A short word, or name.
I am venturing that when Jesus stooped down to write on the ground he wrote the name of a Jewish historic woman; the name "Rahab". And that when he stooped down to write on the ground for the second time he wrote the word of another historic woman; the name "Tamar".
Likely scenario:
What is he doing? He is tracing a word? Can you see what word that is? It is 'R A H A B', - 'Rahab'. That is a name. Yes. It is the name of one of our great, grand mothers. Wasn't she a prostitute? Yes, she was. She was given a second chance . Wasn't she? She was. Well, if our great, grand mother was given a second chance, I suppose that this woman also should be given a second chance. I agree. Let's not pester her anymore. I am going home. Me too. Me too. Me too.
Of course this is all speculative, but I like the idea that what Jesus wrote was:
If a man commits adultery with his neighbor’s wife, both the adulterer and the adulteress shall be put to death. (Lev. 20:10)
Not that I think Jesus would have endorsed stoning the woman if her partner in crime were also accused, but to those who knew the scriptures - as the scribes and Pharisees in the story surely must have - the failure to produce the male adulterer was both hypocritical and illegal. Indeed the wording of the Law makes the male partner the primary culprit. In this scenario the phrase "he who is without sin" may refer to fact that the woman's judges were acting illegally.
So I suggest that Jesus either wrote the text of Lev. 20:10 or something drawing attention to its meaning such "both the man and the woman."
There is a remark in the NIV translation
The earliest manuscripts and many other ancient witnesses do not have John 7:53—8:11. A few manuscripts include these verses, wholly or in part, after John 7:36, John 21:25, Luke 21:38 or Luke 24:53.
Eventually it was put in here should not be a coincident. We can see the narrative before it and after are related to 'Fair Trial'.
Before the incident
Starting from John chapter 7, the narrative told Jesus went to Jerusalem for the Festival of Tabernacles, and was teaching people in the temple courts. His teaching was such an inspiration that even the temple guards who sent to arrest Jesus failed to accomplish their mission. Opinion split amongst people and some Pharisees called Jesus and His disciples 'a mob that knows nothing of the law' (John 7:49). But Nicodemus, who had met Jesus responsed “Does our law condemn a man without first hearing him to find out what he has been doing?” (John 7:51)
After the incident
From John 8:12-20, Jesus declared He is 'the light of the world'. Jesus said
17 In your own Law it is written that the testimony of two witnesses is true. 18 I am one who testifies for myself; my other witness is the Father, who sent me.” (John 8:17-18 NIV)
The incident
It may be interested to note that in chapter 7, John described Jesus inspired people by words, and now facing the challenge of the Pharisees, who intended to prove Jesus knew nothing about the law, Jesus kept silent in response but writing something on the ground. The scripture didn't record what exactly Jesus wrote, but from His established influence in people, Jesus might have wrote something strong enough to push back the people from their original desire.
The narrative described the woman who caught in adultery, was brought forward by her accusers - the teachers of the law and the Pharisees, who claimed be the witness, and the man who be with her, supposed to be the second witness, didn't existed. The group surrounding should have been reminded, that this Trial was deficient in evidence.
What Jesus wrote should have reminded people that 'Judgement belongs to God' (Deu 1:17) - This echoes to Nicodemus response (John 7:51) and Jesus claimed (John 8:18). His writing alerted the elderly people faster, that John described 'they went away one at a time, the older ones first' (John 8:9).
What Jesus had wrote on the ground?
In my opinion, may not be word, but drawing, snakes. Jesus was drawing a snake on the ground, and another snake, and snakes. The public particularly the elders were suddenly aware of Jesus implying Psalm 58, it wrote;
1 Do you rulers indeed speak justly? Do you judge people with equity?
2 No, in your heart you devise injustice, and your hands mete out violence on the earth.
3 Even from birth the wicked go astray; from the womb they are wayward, spreading lies.
4 Their venom is like the venom of a snake, like that of a cobra that has stopped its ears,
5 that will not heed the tune of the charmer, however skillful the enchanter may be.
6 Break the teeth in their mouths, O God; Lord, tear out the fangs of those lions!
7 Let them vanish like water that flows away; when they draw the bow, let their arrows fall short.
In ashame of being the judge and afraid of revenge from the Lord, they went away.
