Know my dear brothers in Islam, that the sin leaves a trace in the heart of the doer as was narrated in the books of hadith. The Prophet, peace be upon him, told us that when a believer commits a sin, then this sin would leave a black dot on his heart. If one repents from that sin then his heart would be cleansed from it, however, if one commits more sins, then this black dot would expand until it covers all his heart. This is what is meant in Ayah 14 of Suratul-Mutaffifin.
So dear brothers in Islam, do not stay away from repentance even if the sin is committed time after another, because the sincere repentance from a sin clears the heart from it.
We do not say that the repentance of one who commits a sin after having been repented of it is not accepted. At-Tirmidhiyy narrated the hadith that the Prophet, peace be upon him, said: <<The majority of the children of Adam would commit sins, and the lucky ones are the ones who repent from these sins after committing them>>.
Brothers in Islam, prepare yourself for the Day of Judgment, the Day in which the mountains will turn into dust and the oceans will be lit in a blaze and dry out.
Remember that Great Day, the Day when no soul shall be able to benefit another in the least (with the exception of the intercession that will take place by the Will of Allah), and the entire matter, that Day, will be with Allah.
On the other hand, do not despair of Allah’s Mercy, even though your sins are numerous. Ayah 53 of Suratuz-Zumar means: [O My slaves who have transgressed against themselves by sinning! Do not despair of the mercy of Allah, for Allah is the One Who forgives the sins and He is the Most Forgiving and Most Merciful].
So do not say Allah will not forgive my sins and will definitely torture me in the Hereafter because of the enormity of my sins. Believing as such is forbidden. How would you know what Allah willed for you on Judgment Day? How would you ascertain that Allah will definitely torture you? The torture of Allah is so severe; however, Allah is also the Most Forgiving and Most Merciful.
This, however, does not mean that you consistently commit the sins relying on the Mercy of Allah and feeing safe from the punishment of Allah without seeking repentance.
On the other hand, one must not despair of the Mercy of Allah and claim that Allah will definitely punish him for his sins, this is also sinful.
My dear Muslim brother, in order for one to be safe from these two sins, one has to be between these two extremes. When one commits a sin, one must be fearful of the punishment of Allah and at the same time be hopeful of the Mercy of Allah.
Dear brothers in Islam, one must repent immediately from a sin whether major or minor. Do not look at a sin as being minor and not repent from it; one must repent because he is disobeying Allah. Therefore, one must not look at how small or enormous the sin is, rather, one should think about whom he is disobeying. So, rush into repenting from both major and minor sins by having the intention of not committing them again and having remorse for not obeying Allah, the One Who created you and bestowed upon you the countless endowments.
Dear brothers, repent and have in your hearts the firm determination of not returning to those sins before you are taken away by death. Ayah 8 of Suratut-Tahrim means: [O you who believe, return to Allah with sincere repentance so you may be forgiven by Allah and admitted into Paradise that has flowing rivers].
If one’s sin was by leaving an obligation, then one must make up that obligation in order for one’s repentance to be accepted. Likewise, if one’s sin was that of depriving a person from his rights, one must give that person his rights in order for his repentance to be accepted.
If a Muslim brother holds any form of grievance against you for instance, if you had sworn at him or taken his money unjustly, then you should liberate yourself from these sins today because the situation on the Day of Judgment is intense; It is a Day when the person flees from his brother, his father and mother, partner and children.
If one owes a right to a person and dies before handing the rights without a valid religious excuse, then the oppressed takes from the good deeds of the oppressor on the Day of Judgment; and if the deeds taken are not enough then the evil deeds of the oppressed are taken and given to the oppressor, consequently the oppressor is then thrown into Hellfire.
So dear Muslim brothers, repent to Allah before death. Repent my dear brother, because death unveils your secrets; the Day of Judgment reveals your actions, and the torture collapses your covers.