The Gospel for Holy Wednesday is John 13:21-32:
"After saying this Jesus was troubled in spirit, and declared, 'Very truly, I tell you, one of you will betray me.' The disciples looked at one another, uncertain of whom he was speaking. One of his disciples -- the one whom Jesus loved -- was reclining next to him; Simon Peter therefore motioned to him to ask Jesus of whom he was speaking.
So while reclining next to Jesus, he asked him, 'Lord, who is it?' Jesus answered, 'It is the one to whom I give this piece of bread when I have dipped it in the dish.' So when he had dipped the piece of bread, he gave it to Judas son of Simon Iscariot. After he received the piece of bread, Satan entered into him. Jesus said to him, 'Do quickly what you are going to do.' Now no one at the table knew why he said this to him. Some thought that, because Judas had the common purse, Jesus was telling him, 'Buy what we need for the festival'; or, that he should give something to the poor. So, after receiving the piece of bread, he immediately went out. And it was night.