Asking Allah by the virtue of So and so
Question

What is the ruling on saying in one’s du`a: ‘O Allah, I ask You by the virtue of So and so’? Is there any difference between this and saying to the occupant of a grave, ‘O So and so, help me!’?
Praise be to Allah.It is not permissible to ask Allah by the virtue of anyone, not even by the virtue of the Prophets or Messengers or awliyaa’ or righteous people. No one can compel Allah to do anything. It is not permissible to ask Him in any way except by His Names and Attributes, as Allah says (interpretation of the meaning):
“And (all) the Most Beautiful Names belong to Allah, so call on Him by them” [al-A’raaf 7:180].
With regard to saying to the occupant of a grave, “O So and so, help me,” this is obviously shirk, because it is a supplication to someone other than Allah. Asking by the virtue of someone is a means to shirk, and calling upon a created being is shirk in worship.
And Allah knows best.