Ibn Mas‘ūd (may Allah be pleased with him) reported: A man was brought to him and it was said: "This is so-and-so, and his beard is dripping with wine." Thereupon he said: "We have been prohibited from spying. However, if we see something evident, we will act upon it."
A man who had drunk wine was brought to Ibn Mas‘ūd (may Allah be pleased with him) and it was clear from his beard, which was dripping with wine, that he had done that. He responded to that by saying that Muslims have been prohibited by Islamic law from spying on others, because it was apparent that the man had drunk it in private, but those people spied on him and brought him in that condition. He added that in case something was obvious and proved by trustworthy witnesses, or the person himself confessed without being spied on, then they would deal with him according to whatever punishment is appropriate, and whoever sought concealment with Allah, then they would not hold him accountable.