Paying to Ask Rabbi Akiva a Question in Prison
With Rabbi Akiva in a Roman prison, the scholars had to pay a man 400 zuz to get in and ask him a halachic question: "our water we drank for money."
The Romans imprisoned Rebbe Akiva. A halachic question arose that no one could answer. They had to pay a man four hundred zuz to somehow get into the prison and ask Rebbe Akiva the question. To get their “water” – namely the Torah – they had to pay a fee. Rav felt that the scholars felt indignant in having to pay for their own Torah.