The return of the unclean spirit (Luke 11:24-26). The connexion in St. Matthew is preferable.
The expulsion of the evil spirit represents the submission of the nation to the baptism of John, which was a baptism of repentance. The sweeping and garnishing of the house represents the superficial but fairly general acceptance of Christ's teaching during the early part of His ministry, to which the Gospels bear witness. The return of the evil spirit with seven other spirits more wicked than himself represents the obstinate and final rejection of Christ by the nation, which was soon to follow, and of which the blasphemy of the Pharisees and their unbelieving demand for a sign were already an earnest.
According to the primary meaning of the parable, the possessed man represents the Jewish nation. But the Christian preacher is quite within his rights when he proceeds to apply it to the individual soul, and to urge the necessity of full and complete repentance, the deceitfulness of merely formal religion, and the danger of relapse. The details of the habits of demons are not to be pressed. Christ adopts the popular phraseology about them as part of the machinery of the parable, without necessarily endorsing it in all respects.