Question- what is the proof that aquiring barakah from Prophet Muhammad's (peace be upon him) grave is permissable is Islam....?

Anwser - Praise be to Allah, and may Allah raise the rank of Prophet Muhammad, peace and blessings be upon him.

Allah made Prophet Muhammad the best of the creation and he made him the most blessed, this means that wherever the prophet is in the place will also have the blessings.

Both Al-Hakim and Adh-dhahabi related that abu Ayyoub visited the grave of the prophet and put his face on one of the walls of the honorable grave.

Imam Ahmad was asked about a man put his hand on the grave of the prophet he answered if he is seeking blessing from the prophet then it is permissible. As mentioned in the book named al-^ilal and knowing the men.

Also there are a lot of evidences showing the permissibility of seeking blessings of the prophet, among of that is the unanimous agreement of the scholars of Islam

And Allah knows best