Passage
And supper being ended, the devil having now put into the heart of Judas Iscariot, Simon’s son, to betray him;
And supper being ended, the devil having now put into the heart of Judas Iscariot, Simon’s son, to betray him;
John 13:1 Now before the feast of the passover, when Jesus knew that his hour was come that he should depart out of this world unto the Father, having loved his own which were in the world, he loved them unto the end.
John 13:2 And supper being ended, the devil having now put into the heart of Judas Iscariot, Simon’s son, to betray him;
John 13:3 Jesus knowing that the Father had given all things into his hands, and that he was come from God, and went to God;
John 13:4 He riseth from supper, and laid aside his garments; and took a towel, and girded himself.
The verse centers on "supper", "ended", "devil", "having", "heart", "judas", "iscariot", and "simon". It is saying that the verse draws attention to "supper" and "ended", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 1's "Now before the feast of the passover..." into verse 3's "Jesus knowing that the Father had given...", so "supper" and "ended" 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 "ended" with trust shaped by these words, not by a vague optimism outside the passage.