Anybody else who are interested about the agrapha?
To put it simply, agrapha (Greek for “not written”; singular agraphon) are sayings attributed Jesus that are not found in the canonical Gospels but instead appear in other sources, such as other books of the New Testament or even outside the Bible, quoted by early Christian writers.
A prime example of this is in Acts 20:35, where St. Paul says:
In all things I have shown you that by working hard in this way we must help the weak and remember the words of the Lord Jesus, how he himself said, ‘It is more blessed to give than to receive.’”
This saying is not found in the Gospels.
There are actually quite a lot of agrapha, many of which are quoted by the Fathers and other Christian literature. Some had a penchant for quoting them extensively, like Clement of Alexandria, whose Stromata is literally dotted with these sayings:
For He says, “Have you seen your brother? You have seen your God.” (1.19)
For He says, “Ask for the great things, and the little things will be added unto you.” (1.24)
With reason, then, the scripture, wishing us to become such kind of dialectics, exhorts: “But become approved moneychangers, rejecting the [evil] things, and embracing the good.” (1.28)
And again the Lord says, “Let the one who has married not be cast out, and let the one who has not married not marry. He who has confessed that he will not marry according to his decision of eunuchhood, let him remain unmarried.” (3.15)
Finally, there is also this one anecdote which St. Irenaeus and St. Hippolytus of Rome record about Judas and Jesus.
The blessing thus predicted pertains, without [fear of] contradiction, to the times of the kingdom, when the just, rising from the dead, will reign, when even the creation, renewed and liberated, will produce a multitude of foods of all kinds from the dew of heaven and the fertility of the earth, just as the elders who saw John the disciple of the Lord remembered that they had heard from him how the Lord would teach about those times and would say:
“The days will come in which vines will grow, each having ten thousand shoots, and on each shoot ten thousand branches, and on each branch ten thousand twigs, and on each twig ten thousand clusters, and in each cluster ten thousand grapes, and each grape, when pressed, will give twenty-five measures of wine. And, when one of those saints takes hold of a cluster, another cluster will clamor: ‘I am better, take me, bless the Lord through me!’
Similarly a grain of wheat also will generate ten thousand heads, and each head will have ten thousand grains, and each grain five double pounds of clear and clean flour. And the remaining fruits and seeds and herbiage will follow through in congruence with these, and all the animals using these foods which are taken from the earth will in turn become peaceful and consenting, subject to men with every subjection.”
These things Papias too, who was a earwitness of John and companion of Polycarp, and an ancient man, wrote and testified in the fourth of his books. For there are five books written by him. And he adds, saying: But these things are believable by the believers. And, he says, Judas the traitor did not believe and asked: “How therefore will such generations be brought to completion by the Lord?” The Lord said, “Those who come into those [times] will see.”
(Irenaeus, Against Heresies 5.33.3-4)
When therefore the Lord narrated to the disciples that the imminent kingdom of the saints would be glorious and wondrous, Judas, bewildered by these words, said, “And who will see these things?” But the Lord said: “Those who have become worthy will see these things.”
(Hippolytus, Commentary on Daniel 4.60)
If authentic, these are the testimonies to that little portion of the Gospel of John which records that not everything Jesus said or did was recorded down.