The words of Jesus are heard only by John and even he does not understand their importance. He was probably still looking for the betrayer to do so by accident in the far future. Note that Jesus does not want the group as a whole to know who the traitor is. Why not?

The sop consisted of a piece of the roasted Paschal lamb, a piece of the unleavened bread, and some of the bitter herbs, which were dipped into the dish containing the charoseth.

For a host to give a guest a special morsel was a sign of honor and close friendship (Ruth 2:14). T.E. Lawrence told of how he sat in the tent of an Arab chief and his host would tear the choicest piece of mutton from the sheep and hand it to him, as a sign of great favor. The handing of the sop to Judas was a sign to John of identity of the traitor, but it was also the last appeal of love by Jesus to all that was human in Judas. As Barclay says, “May God save us from being completely impervious to the appeal of love.”

Ruth 2:14  At mealtime Boaz said to her, “Come over here. Have some bread and dip it in the wine vinegar.” When she sat down with the harvesters, he offered her some roasted grain. She ate all she wanted and had some left over.