The oven of Akhni is a story told in the Talmud, tractate Bava Meziah 59b. The Rabbis are having an argument about a technical point of law; whether a particular type of oven is pure or impure.

This story is often quoted by Rabbis and Jewish educators. It makes the point that humanity has been given a large amount of autonomy and control over law, right and wrong; and it reinforces the basic principles of interpretation of Jewish Law.

R. Eliezer declared [the oven] pure, but the [other] Sages maintained it was impure. R. Eliezer brought every possible argument, but they rejected it.

He said to them "If the Halacha (law) agrees with me, let this carob tree prove it". The carob tree was then ripped out the ground and flew 100 (or maybe 400) cubits. They replied to him "You can't prove a point of law using a carob tree".

He said to them "If the Halacha agrees with me, let this stream prove it". The stream suddenly started to flow backwards. They replied to him "You can't prove a point of law using a stream".

R. Eliezer carried on, saying "If the Halacha agrees with me, let this walls of the study house prove it". The walls started to cave inwards. R. Yehoshuah told off the walls and said "When scholars are having a legal dispute, what right do you have to get involved?". The walls stopped caving in out of respect for R. Yehoshuah, but didn't straighten out of respect for R. Eliezer (they are still curved to this day).

Desperate, R. Eliezer said If the Halacha agrees with me, let heaven prove it". Suddenly, a voice from heaven said "Why are you arguing with R. Eliezer, don't you know that his rulings always right?"

R. Yehoshuah got to his feet and said "[The Torah] is not in heaven! (Deut 30:12])" What did he mean? R Yirmia explained that the Torah had already been given, at Sinai. We don't pay any attention to a voice from heaven, as You wrote in the Torah given at Sinai that "After the majority must one incline (ex 23:2)".

The law went the way of the Sages, and R. Eliezer lost. But who was actually in the right? This story has a little more to it to answer that question.

R. Natan met Elijah the prophet and asked him "What did the Holy One do then?"
Elijah answered "He laughed, and said 'My children have defeated me, my children have defeated me!'"