King James Bible
"And supper being ended, the devil having now put into the heart of Judas Iscariot, Simon’s son, to betray him;"
This refers to the conclusion of the Last Supper, the final Passover meal Jesus shared with his disciples. The timing is significant—the intimate fellowship of the meal has concluded, and the events leading to the crucifixion are now set in motion. John reveals the spiritual warfare behind Judas's betrayal, attributing the evil intention to Satan's influence. The phrase suggests that while Judas retained moral responsibility, his heart had become receptive to demonic suggestion through prior choices and attitudes. The full identification of Judas by his father's name adds a note of tragic irony—this betrayer was one of the Twelve, fully known and chosen by Jesus. The verse ends with the stark reality that one from Jesus's inner circle would deliver him to death.