Passage
And when supper was done (the devil having now put into the heart of Judas Iscariot, the son of Simon, to betray him),
And when supper was done (the devil having now put into the heart of Judas Iscariot, the son of Simon, to betray him),
John 13:1 Before the festival day of the pasch, Jesus knowing that his hour was come, that he should pass out of this world to the Father: having loved his own who were in the world, he loved them unto the end.
John 13:2 And when supper was done (the devil having now put into the heart of Judas Iscariot, the son of Simon, to betray him),
John 13:3 Knowing that the Father had given him all things into his hands and that he came from God and goeth to God,
John 13:4 He riseth from supper and layeth aside his garments and, having taken a towel, girded himself.
The verse centers on "supper", "done", "devil", "having", "heart", "judas", "iscariot", and "simon". It is saying that the verse draws attention to "supper" and "done", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 1's "Before the festival day of the pasch..." into verse 3's "Knowing that the Father had given him...", so "supper" and "done" belong inside that flow. In John context, the local focus is the identity of Jesus, new birth, eternal life, and belief and unbelief.
A plain takeaway is to answer the verse's own emphasis on "supper" and "done" with trust shaped by these words, not by a vague optimism outside the passage.