Allah Almighty says: {Do not spy on one another} [Surat al-Hujurāt: 12] He also says: {Those who abuse believing men and women for something they did not commit, they will bear the burden of slander and flagrant sin.} [Surat al-Ahzāb: 58]
Spying: pursuing people's faults, and seeking to disclose them.
1) It is forbidden to pursue the private matters of Muslims as it is one of the major sins.
2) Intentional listening to others’ talk – while they dislike this – is a form of great harm that Allah has forbidden.
1570/1 - Abu Hurayrah (may Allah be pleased with him) reported that the Prophet (may Allah’s peace and blessings be upon him) said: “Beware of suspicion, for suspicion is the most untrue speech. Do not look for the faults of one another, do not spy on one another, do not compete against one another, do not envy one another, do not harbor hatred for one another, do not shun one another, and be, O slaves of Allah, brothers to one another as He commanded you. A Muslim is the brother of a Muslim. He should neither oppress him nor fail him nor humiliate him. Piety is here! Piety is here!” While saying so he pointed to his chest. “It is enough evil for a Muslim to look down upon his Muslim brother. All things of a Muslim are inviolable to his brother in faith: his blood, his wealth, and his honor. Verily, Allah does not look to your bodies nor to your images but He looks to your hearts and your deeds.”
Another narration reads: “Do not envy one another, do not harbor hatred for one another, do not spy on one another, do not search for the faults of one another, do not commit Najsh (artificially inflating the price) against one another, and be, O slaves of Allah, brothers.”
According to another narration: “Do not sever ties with one another, do not turn your backs on one another, do not harbor hatred for one another, do not envy one another, and be, O slaves of Allah, brothers.”
In another narration: “Do not desert one another, and do not enter into a transaction which is already concluded with someone else.”
[All these versions were narrated by Muslim, and most of them were narrated by Al-Bukhāri]
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Najsh or Tanājush: bidding to raise the price without the intention to buy (to artificially inflate the price) in order to cheat others.
1) A severe warning against violating the sanctity of Muslims’ blood, honor, and wealth.
2) Prohibiting spying and eavesdropping, and anything that sows disunity among the believers.
3) Good deeds are the outcome of having good hearts and intentions, So, be keen on having sincerity in all your words, deeds, and affairs.
1571/2- Mu‘āwiyah (may Allah be pleased with him) reported: I heard the Prophet (may Allah’s peace and blessings be upon him) say: “If you pursue the faults of the Muslims, you will surely corrupt them, or you will nearly corrupt them.” [Narrated by Abu Dāwūd with an authentic Isnād; Sahīh (authentic)]
1) The Hadīth warns against spying on the Muslims for the purpose of pursuing their faults as this causes the spread of corruption between them.
2) One of the positive aspects of the Islamic Shariah is that it warns against all that brings about corruption between Muslims.
1572/3- A man was brought to Ibn Mas‘ūd (may Allah be pleased with him) and it was said: “This is so-and-so, and his beard is dripping with wine.” Thereupon he said: “Verily, we have been forbidden from spying; but if something is evident (i.e. if a sin is committed openly), we will act upon it.”
[Narrated by Abu Dāwūd with an Isnād that meets the conditions of Al-Bukhāri and Muslim]
1) If someone makes a claim against another, basing it upon spying, his claim is rejected.
2) The Hadīth encourages concealing the sinner who does not commit sin in public to give him a chance to repent of it.