Talmud for Ketubot 11:5

HALAKHAH: “Rebbi Yose ben Rebbi Jehudah says,” etc. Rebbi Hoshaia stated: The following verse is said about two groups of witnesses. If an oppressive witness arises against a man, a plotting witness who answers to a man. Answering him, not his testimony⁶⁶While testimony may not stand up under cross-examination, the worst that can happen to a witness in that case is that the court does not believe him. A criminal conviction can only follow if the new group of witnesses answer him, the plotting witness, by showing that he could not have been present at the place of the alleged crime or transaction. This paragraph belongs to Mishnah 6.. Do plotting witnesses have to be warned? Rebbi Isaac bar Tevlai in the name of Rebbi Eleazar: Plotting witnesses do not have to accept warning⁶⁷In the Babli, Ketubot 32a, this is an anonymous statement accepted without discussion.. Rebbi Abbahu said, we do not take notice of this. Rebbi Jacob bar Dassai said, and there are very cunning people who even if they see their comrades being led out to be killed do not say anything⁶⁸It is not clear whether this statement supports R. Eleazar or R. Abbahu. In the first case, he argues that a special warning about penalties of plotting perjury is unnecessary since the bad guys automatically will stay away as far as possible from the court. In the second case he wants to point out that good people will not be kept away from being witnesses by being admonished by the court about penalties of plotting perjury, and it is a good thing that bad people will be frightened away..