Chapter 1, Mishnas 6, 7
Rav Pappa and and Rav Huna the son of Rav Yehoshua disagree on an enclosure of mechitzos, partitions, where the standing portions exactly equal the breached portions. Rav Pappa is wrong AND the law follows Rav Pappa! How big can an enclosure be to permit carrying on Shabbos? Some say two beis se’ah – the amount of land needed to grow two measures of grain, same as the size of the courtyard of the Tabernacle, about 5000 square cubits or about 100 feet by 100 feet. Some say six beis se’ah. The law for three or more people making an enclosure is that they assume the legal status of a caravan and they can make as big an enclosure as they want, but it’s disqualified if it’s over six beis se’ah and includes an unoccupied, unenclosed area of two beis se’ah within it. Rav Nachman made a mistake and hired a loudmouthed “speaker” to help him publicize the error so people wouldn’t rely on his mistake and come to make a Shabbos transgression.