Two witnesses testified that one person murdered another. Later another set of witnesses came and contradicted the first, and then also made them false witnesses by saying that “you were with us in a different place at this time and therefore could not have witnessed the murder”.

Rabbi Yochanan says that the first witnesses are executed, for although their testimony was invalidated and set aside, and they stopped being witnesses, they are still punished as false witnesses. Rabbi Elazar says that they are not executed, because the rule of “contradiction is the beginning of making witnesses false” is not true.