john 13:27 And after the sop Satan entered into him. Then said Jesus unto him, That thou doest, do quickly. - Free Bible Online

      27-30. after the sop Satan entered into him--Very solemn are these brief hints of the successive steps by which Judas reached the climax of his guilt. "The devil had already put it into his heart to betray his Lord." Yet who can tell what struggles he went through ere he brought himself to carry that suggestion into effect? Even after this, however, his compunctions were not at an end. With the thirty pieces of silver already in his possession, he seems still to have quailed--and can we wonder? When Jesus stooped to wash his feet, it may be the last struggle was reaching its crisis. But that word of the Psalm, about "one that ate of his bread who would lift up his heel against Him" (Ps 41:9) probably all but turned the dread scale, and the still more explicit announcement, that one of those sitting with Him at the table should betray Him, would beget the thought, "I am detected; it is now too late to draw back." At that moment the sop is given; offer of friendship is once more made--and how affectingly! But already "Satan has entered into him," and though the Saviour's act might seem enough to recall him even yet, hell is now in his bosom, and he says within himself, "The die is cast; now let me go through with it"; fear, begone!" (See on Mt 12:43).
      Then said Jesus unto him, That thou doest, do quickly--that is, Why linger here? Thy presence is a restraint, and thy work stands still; thou hast the wages of iniquity, go work for it!

JFB.