IF IT WAS PUT IN A CUPBOARD AND THE KEY WAS LOST THE ERUV IS NEVERTHELESS EFFECTIVE. R. ELIEZER RULED: IF IT IS NOT KNOWN THAT THE KEY IS IN ITS PROPER PLACE THE ‘ERUB IS INEFFECTIVE.
The discussion focuses on a brick cupboard, loosely constructed so that in theory it could be breeched and the meal removed. At issue is also the key itself. If the key is lost in the town and then found – in theory it could be carried to the cupboard by way of rooftops and other permitted areas. But if were lost in the countryside, even if it were found it could not be brought on Shabbat.
[Some words] indeed are missing [from the Baraitha] and this is the proper reading: If it was put In a cupboard and locked up and the key was lost the eruv is effective. This ruling, however, applies only to a festival but on a Sabbath the eruv is ineffective. [Even] if the key was found, whether in town or in a field, the eruv is ineffective.
R. Eliezer ruled: [If it was found] in town the eruv is effective; if in a field it is ineffective. ‘In town the ‘erub is effective’ in agreement with R. Simeon who laid down that roofs, courtyards as well as karpafs (storage areas) have the status of the same domain in respect of objects that rested in them.
In a field it is ineffective in agreement with the Rabbis.