Musannaf Ibn Abi Shaybah

Hazrat Zaid bin Wahb narrates that someone was brought to Hazrat Ibn Mas’ud and it was told to him that drops of wine were dripping from so-and-so’s beard! Upon this, Hazrat Abdullah bin Mas’ud (may Allah be pleased with him) said: Indeed, we have been forbidden from spying. But if a matter becomes apparent before us, then we will hold him accountable for it.