daf bit: Avodah Zarah 61
Oct. 14th, 2010 08:55 amThe mishna teaches: if an Israelite prepares a gentile's wine in a state
of ritual purity and leaves it in the gentile's domain, in a house which
opens on the public domain, then it is permitted for benefit to the
Israelite if and only if Israelites live in the town along with the
gentiles. If only gentiles live there it is forbidden unless an
Israelite watches it, though the watching does not need to be 24x7. (61a)
The rabbis' concern is that the gentile will use the wine for idolatry, which disqualifies it for any use by Jews (including payment for sale or production). However, the presumption is that if the house is open to some amount of public view, the gentile won't do so for fear of being caught.