وَلَوْ أَنَّهُمْ إِذ ظَّلَمُوا أَنفُسَهُمْ جَاءُوكَ فَاسْتَغْفَرُوا اللَّهَ وَاسْتَغْفَرَ لَهُمُ الرَّسُولُ لَوَجَدُوا اللَّهَ تَوَّابًا رَّحِيمًا
If, when they had wronged themselves, they had come to you – O Muhammad (صلى الله عليه و سلم) – and had sought Allaah’s forgiveness, and the Messenger had asked for Allaah’s forgiveness for them, then they would have found that Allaah would have accepted their repentance and had mercy upon them. [Sooratun-Nisaa (4): 64]
Ibnul-Qayyim (rahimahullaah) said:
“Since Allaah – the One free of all imperfections – knew that those to whom the Messenger was sent would certainly wrong themselves and follow their desires, He guided them to that which would repel the evil of that wrong and remove its causes. This lay in two things:
Firstly, there was something that they themselves were to do, which was to seek forgiveness of their Lord – the Mighty and Majestic.
Secondly, there was something for someone else to do, and this was that the Messenger (صلى الله عليه و سلم) should ask forgiveness for them when they came to him, submitted obediently to him and acknowledged their wrong-doing. So, if they were to do these two things, they would find that Allaah would accept their repentance and forgive them. He would accept their repentance, thus wiping away the effect of their sins and protecting them from their evils. In addition to this, He would grant them His Mercy, His favourable and fine treatment.
So, what share of this Aayah is there for a person who wrongs himself after the death of the Prophet (صلى الله عليه و سلم) ? Does the use of the Aayah support those people who claim that the person should go to his (صلى الله عليه و سلم) grave; ask for forgiveness there, and for his intercession?
The reply is that, as for the share of the person who wrongs himself after the death of the Prophet (صلى الله عليه و سلم) with regard to this Aayah, he should ask for Allaah’s forgiveness, with sincere repentance and this applies in every time and place. It is not a condition for the correctness of his repentance that he should go to his (صلى الله عليه و سلم) grave, and ask for forgiveness there. (By consensus- Ijmaa”).
As for going to his grave and seeking forgiveness there and seeking his intercession, using this Aayah as an evidence, then the Aayah does not indicate this in any sense at all. It only refers to going to him (صلى الله عليه و سلم) ; not going to his grave; nor does it state that he will seek forgiveness for them if they seek intercession from him after his death.
This is thus shown to be a false and futile argument which is further clarified by the fact that the Companions, those who of all people knew best about the Book of Allaah and the Sunnah of His Prophet (صلى الله عليه و سلم) , did not understand the Aayah in this way. So it is known that this is an innovation. That which is most frequently used as evidence by those who permit it, is the narration of al-`Utabee from an unknown Bedouin, even though we do not know any chain of narration for it. If this disconnected report, or it’s like, were a hadeeth or a report from a Companion, then it would not be permissible to use it as a proof, and its ruling would not be binding upon us because of its lack of authenticity. How then can it be permissible to use as proof for this a story that is not authentic, concerning a Bedouin who is unknown!? 
Shaikh ‘Abdur-Rahmaan ibn Naasir as-Sa`dee (rahimahullaah) said:
Meaning: If, when they had wronged themselves, they had come to you – O Muhammad (صلى الله عليه و سلم)
i.e. acknowledging their sins, and fully confessing them.
“…and had sought Allaah’s forgiveness, and the Messenger had asked for Allaah’s forgiveness for them, then they would have found that Allaah would have accepted their repentance and had mercy upon them”
i.e. He would have turned to them, forgiven their wrongdoing, and been Merciful to them; by accepting their repentance, guiding them to it and granting it to them, and rewarding them for it. This coming to the Messenger (صلى الله عليه و سلم) was something specific to his lifetime.
This is what the context indicates, because seeking forgiveness from the Messenger cannot occur except in his lifetime. As for after his death, then nothing can be sought from him; rather that would be shirk.” 
 Tayseerul-‘Azeezil Hameed Sharh Kitaabit-Tawheed of Shaikh Sulaymaan ibn `Abdillaah ibn Muhammad bin `Abdul-Wahhaab (pp. 561-562)
 Tayseerul-Kareemir-Rahmaan fee tafseer Kalaamil-Mannaan of Shaikh “Abdur-Rahmaan ibn Naasir asSa”dee.
[Translated by Aboo Talhah Daawood ibn Ronald Burbank –rahimahullaah]
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