Avodah Zarah

A citron once fell into a cask of wine, and a heathen sprang for ward to pull it out. R. Ashi said to them:  Hold his hand so that he does not splash about,  and tilt [the cask] until it is emptied. R. Ashi said: When a heathen has deliberately rendered the wine of an Israelite nesek, although it is prohibited to sell it to another heathen, [the owner] is allowed to receive the cost from the person [who disqualified it]. On what ground? — Because he involved him in a loss.  R. Ashi said: Whence do I derive this? — From this teaching: If an idolater offered wine of an Israelite [as a libation], not in the presence of an idol, it is prohibited; but R. Judah b. Baba and R. Judah b. Bathyra permit it  for two reasons: first, because wine can be rendered nesek only in the presence of an idol, and secondly because [the owner can] say to him, 'You have no right to make my wine prohibited through no fault of my own.' It once happened that the bung fell out of a cask of wine, and a heathen sprang forward and placed his hand over it, R. Papa said: All the wine that is on the level with the bung-hole is prohibited