Hadith

“A Muslim is a brother for (another) Muslim. He must not oppress him nor must he abandon him (in some difficulty or allow someone to oppress him). The one who occupies himself in solving the problem of his brother, Allah will solve his problem. The one who relieves a Muslim of a difficulty, Allah will relieve him of one difficulty among the difficulties of Qiyamah. The one who conceals the shortcomings of a Muslim, Allah will conceal his shortcomings on the day of Qiyamah." (Saheeh Bukhari / Saheeh Muslim)

Explanation:

Allah Ta’ala has established the bond of brotherhood between Muslims. As a result, a Muslim is supposed to live with another Muslim just as he lives with his real brother. On the contrary, Islam considers the bond of brotherhood that has been established on the basis of Imaan, stronger than that of blood relationship. That is why we see that Allah Ta’ala refused to accept the real son of Hazrat Nuh (Alaihis Salaam) as a member of his family just because he was not a Muslim. Thus, just as a person is sincere with his own brother, he must act in the same way with his Muslim brother. A person normally supports his brother. Similarly, a Muslim should support his Muslim brother. He must not oppress him nor allow others to oppress him. 

ظلم or oppressing means depriving someone of his right. The life, honour, family and wealth of every Muslim are sacred to the next Muslim. Therefore, a Muslim does not have the right to deprive another Muslim of his right nor does he have the right to remain insensitive when that is being violated. He must always be ready to help his Muslim brother according to his ability.

A person benefits enormously by helping his Muslim brother because according to this Hadith, Allah Ta’ala continues to help a person as long as he helps the next person. 

According to a Hadith found in Saheeh Muslim, Rasullullah (Sallallaahu Alaihi Wasallam) said:

"والله فى عون العبد ما كان العبد فى عون اخيه"

"Allah continues to help a servant as long as this servant is engaged in helping his (Muslim) brother."

Similarly, a person who consoles his brother who is in a problem and relieves him of his difficulty, will be relieved of his difficulty on the day of Qiyamah. Thus, a person renders himself fortunate in this Dunya and in the Aakhirah by helping the next person and relieving him of his problem. This shows that when a person causes harm to the next person, in reality, he harms himself and renders himself miserable because he deprives himself of the assistance of Allah Ta’ala in the Dunya and in the Aakhirah. When a person does not cooperate with his Muslim brother, it is a way of turning the back on the help of Allah Ta’ala.

... Concealing the shortcomings of a Muslim...

The honour of a Muslim also is sacred. Thus, a Muslim must always conceal the shortcoming of his Muslim brother and he must not do anything that would dishonour him. A person, who conceals the shortcoming of his Muslim brother, will receive the same treatment by Allah Ta’ala on the day of Qiyamah. That is, Allah Ta’ala will not reveal his shortcomings on the day of Qiyamah. Allah Ta’ala will preserve his honour just as he has preserved the honour of his Muslim brother. According to a Hadith, a person who searches for the shortcoming of his friend, Allah Ta’ala will dishonour him even if he remains hidden in his house. This leads us to understand that a person protects his own honour by concealing the shortcoming of his friend. A person causes himself immense harm by disclosing the sins of his friend and by denigrating him. It is as if we are all in one boat. By drowning the boat of our friend, we will also drown. Or it is like we are all hanging on one branch. By cutting the branch, we will also fall and suffer. This shows that a person who harms the next person is very stupid. He is so stupid that he does not know that he is harming himself.

... an exception...

But there are circumstances where it becomes necessary to disclose the shortcoming of a person because by concealing it, one may harm the next person and induce him in error.

• The first example:

A person who did not study Deen but is claiming to be a great scholar. Thus, one must expose such a person so that it does not become a source of Fitna and a means of deviation.

• The second example:

A person wants to get information about a person to whom he intends sending a marriage proposal. It is the duty of the person who is giving this information not to hide anything and to say the whole truth. He must not conceal anything. In such a circumstance, hiding something will represent treason and dishonesty towards that person.

Therefore, in principle, one must hide the shortcoming of a person as long as it does not become a threat or a danger to the interest of another person or the Deen.

... Be careful / Beware!

However this is a very dangerous step because a person can use Deen as an excuse to satisfy his personal grudge. He may be exposing his brother due to his personal “grudge” but he presents under the cover of Deen. We must not forget that Allah Ta’ala knows our intention and we will be accountable by Him.

[English version of "Ene musulman li ene frère pou ene (l'autre) musulman" – Al Jamiat – Vol.4 No.2]