Sanhedrin 68 - Wayward and Rebellious Son
Rabbi Eliezer once taught Rabbi Akiba the act of magic with cucumbers: by saying a few words, he had planted a field full of cucumbers, and by saying a few other words he made them collect into one place. How was he allowed to practice witchcraft, if it says, " You shall not learn to do it "? - Because you can learn in order to understand and teach.
However, that was the only piece of knowledge that Rabbi Akiba learned from him after Rabbi Eliezer was excommunicated for not following the law accepted by the majority. When Rabbi Eliezer was dying, he predicted that the Sages who did not realize their full learning potential because of not learning from him would die a martyr's death, and it came true.
A wayward and rebellious son is a boy who commits certain sins associated with theft and gluttony. If his parents admonish him and he ignores their warnings, he is flogged in court. If he still persists in his behavior, he is put to death through stoning.
Art: Antonio Mancini - The Poor Schoolboy