Avodah Zarah 58 - Two Contradictory Rulings about Wine, Both Correct
Rabbi Yochanan ben Arza and Rabbi Yose ben Nehorai were sitting and drinking wine. A waiter, whom they took to be a Jew, came by, and they asked him to pour them a drink. After he poured the wine into theirs cups, it transpired that he was an idol worshipper. One of the Rabbis ruled the wine prohibited even for benefit, while the other one ruled it permitted even for drinking.
Said Rabbi Yehoshua ben Levi, "The one who prohibited did well, and the one who permitted also did well."
The one who prohibited reasoned as follows: the idolater thought, "Is it conceivable that such distinguished Rabbis such as these would drink beer? - No! It must be wine!" - and having ascertained this, he intended to make a libation for his idol.
The one who permitted reasoned as follows: the idolater thought, "It is conceivable that such distinguished Rabbis would be drinking wine and ask me, an idolater, to pour wine for them? - No! It must be beer!" Since he knew that it was wine, he did not make a libation.
Art: Friedrich Friedlander - The Wine Tasting or A Good Vintage