In Luke 16, Jesus says that if they refuse to listen to the Bible, then even if they see something miraculous they will not be convinced. Jesus is addressing the Pharisees, who were lovers of money (Luke 16:14). In verses 19-31 he gives them a shocking warning in the parable of the rich man and Lazarus. The rich man dies and is in torment in Hades (verse 22-23), upon finding himself in this irreversible torment (verses 25-26) he longs that his brothers be warned so that they might repent before they face the same (verses 27-28). The answer comes back "They have Moses and the prophets [i.e. the Scriptures]; let them hear them." (verse 29). Lazarus insists: "No,...but if someone goes to them fro the dead, they will repent." (verse 30). To which Abraham replies "If they do not hear Moses and the Prophets, neither will they be convinced if someone should rise from the dead." (verse 31).
The Bible is sufficient for belief. We do not need anything else to convince us and to bring us to repentance. J. C. Ryle has these helpful and challenging words to say on this in his 'Expository Thoughts' on Luke:
The Scriptures contain all that we need to know in order to be saved, and a messenger from the world beyond the grave could add nothing to them. It is not more evidence that is wanted in order to make men repent, but more heart and will to make use of what they already know. The dead could tell us nothing more than the Bible contains, it they rose from their graves to instruct us. After the first novelty of their testimony was worn away, we should care no more for their words than the words of any other. This wretched waiting for something which we have not, and neglect of what we have, is the ruin of thousands of souls. Faith, simple faith in the Scriptures which we already posess, is the first thing needful to salvation. The man who has the Bible, and can read it, and yet waits for more evidence before he becomes a decided Christian, is decieving himself. Except he awakens from his delusion he will die in his sins.Taken from 'Expository Thoughts on Luke'.