Imaam Abu al-Wafaa? ibn ^Aqeel al-Hanbaliyy (who is one of the pillars- as they say- of the Hanbaliyy school of thought) said that among what is liked to say when visiting the Prophet?s grave is what means:
?O Allaah, You said in Your Book to Your Prophet:
(Verse 64, Surat an-Nisaa? means: {If only, when they are unjust to themselves, they come to you and ask Allaah for forgiveness, and the Messenger asks forgiveness for them, they will find that Allaah is Forgiving and Most Merciful.}) and I have come to Your Prophet repented and asking for Your forgiveness, so I ask You to forgive me as You gave forgiveness to those who came to Your Prophet during his lifetime. O Allaah, I direct myself to You by Your Prophet Sallallaahu 3alayhi wa sallam, the Prophet of mercy, O Prophet of Allaah, I direct myself by you to my Lord for Him to forgive my sins.?
Al-Bayhaqiyy narrated with a SaHeeH chain from Maalik ad-Daar (a trustworthy person appointed by ^Umar during his caliphate) that he said what means:
?There was a drought (for 9 months) in the time of the caliphate of ^Umar. A man from the companions came to the grave of the Prophet Sallallaahu 3alayhi wa sallam and said: ((O Prophet of Allaah, ask rain for your nation for they are in ruins)). That companion saw the Prophet in his dream saying to him what means: ((Send my salaam to ^Umar and tell him that it will rain and tell him to try his best to serve the nation.)) The companion went to ^Umar and told him. ^Umar cried and said what means: ((O Allaah, I will not fall short in trying to serve the nation.))?
This companion was said to be Bilaal ibn al-Haarith al-Muzaniyy.
The caliph al-Mansoor when he made Pilgrimage and visited the Prophet asked Imaam Maalik ((O father of ^Abdillaah, should I face the Quiblah and supplicate or should I face the Prophet of Allaah Sallallaahu 3alayhi wa sallam?)). Imaam Maalik said: ?And why would you not face him when he is the one you ask Allaah by and the one your father Adam ^alayhis-salaam asked Allaah by? Face him and seek his intercession and Allaah will allow him to intercede.?
This was mentioned by Qaadee ^IyaaD in the book ?Ash-shifaa?.Asking Allaah by the Prophet = seeking to gain benefit or alleviate harm, from Allaah, by mentioning a Prophet in honour of the mentioned, with the firm belief that Allaah is the Creator of benefit and harm.
In the Hadeeth related by al-Bukhaariyy in al-Adab al-Mufrad: when Ibn ^Umar?s leg became paralysed, in his call for help he said: ?O MuHammad.? His call was answered with a cure.