None of those at the table understood why he said this to him.
In context
26Jesus answered, “It is the one for whom I will dip this piece of bread and give it to him.” Then he dipped the piece of bread, and he gave it to Judas, son of Simon Iscariot. 27And with the bread, Satan entered him. Jesus said to him, “What you are doing, do quickly.” 28None of those at the table understood why he said this to him. 29Since Judas kept the money box, some thought Jesus was telling him, “Buy what we need for the festival,” or to give something to the poor. 30As soon as he had taken the bread, he went out. And it was night.
