Allah Most High says, {And spy not on each other.} (Al-Hujurat: 12)

The meaning of this command is that a Muslim should avoid searching about his brother's faults that Allah has concealed.

Once a man said to Ibn Mas'ud (may Allah be pleased with him), "This man, Al-Walid Ibn 'Uqbah, seems to be drunk for the traces of wine appears on his beard." Ibn Mas'ud replied, "We are commanded to avoid spying but when something ascertained to us we judge accordingly.” The Messenger of Allah (pbuh) declared, "Whoever listens to people who are averse to his listening shall have molten lead poured into his ears on the Day of Judgment.”1