Shua’b ul Iman by Imam Bayhaqi, Publish: Maqtabah ar-Rashad, Riyadh/Saudia
[Hadith Number 3879] Abu Ishaq al-Qarshi (ra) narrates that there was a man with us in Madina. Whenever he used to see any bad deed which he was not capable of stop with his hand, he used to go to the grave of Prophet (Peace be upon him) and say: O the inhabitants of Qabr i.e. Prophet and Sahaba (Abu Bakr and Umar) and our helpers please look towards our state. — [Hadith Number 3880] Abu Harb Hilali (ra) narrates that one Arabi performed Hajj and then came to the door of Prophet’s Mosque. He tied his camel there and enter the mosque till he reached the grave of Prophet (Peace be upon him). He stood at the feet of Prophet (Peace be upon him) and said: Peace be upon you O Prophet, then he offered greetings to Abu Bakr and Umar (Ridhwan Allaho Ajmain), he then turned towards the Prophet again and said: …O Messenger of Allah, May my parents be taken ransom for you, I have come in your court because I am filled with sins and mistakes, so that I can make you a waseela infront of Allah so that you can intercede for me, because Allah has said in his Book: And We have not sent any Messenger but that he must be obeyed by the Command of Allah. And, (O Beloved,) if they, having wronged their souls, had come to you imploring the forgiveness of Allah and the Messenger (blessings and peace be upon him) had also asked forgiveness for them, then (owing to this mediation and intercession) they would certainly have found Allah Most Relenting, Ever-Merciful. (Quran 4/64)” Then he turned towards a big group of Sahaba while saying: O best of those who are buried in deep””And from whose fragrance the depth and the height have become sweet” “May I be the ransom for a grave which thou inhabit” “And in which are found purity, bounty and munificence!” [Shuab ul Iman Volume 006, Page No. 60 Hadith Number 3879-80]
Majorrity Scholers took this report as proof in Tawassul which means it is accepted (Maqbool). and Allah Knows Best.