William Burkitt on John 13:21

Oh what an astonishing word was this, One shall betray me! one of my disciples shall betray me! yea, One of you, my disciples and apostles, shall do it! well might they look one upon another with sorrow and amazement, to hear that their master should die, that he should die by treason, and that the traitor should be on of themselves; yet do they not censure one another, but suspect themselves, saying, Master, is it I? not Master, is it Judas?

Learn hence, 1. That it is possible for secret wickedness to lurk, yea, for the greatest villainy to lodge in the hearts of professors, in whose conversations appeareth nothing that may give a just suspicion to others.

Learn, 2. That it is both the duty and property of the disciples of Christ to have so much candour and brotherly love, as not rashly to censure, and judge one another, but to hope the best of others, and to fear the worst of themselves.