What is the ruling on seeking intercession and forgiveness from the Prophet, peace and blessings be upon him, after his death: Is it polytheism (shirk) or innovation (bid'ah), and is there a disagreement among the four imams on this issue?

Seeking supplication from the Prophet, peace and blessings be upon him, after his death is impermissible; it is an innovation (bid'ah) and a means leading to polytheism (shirk). None of the predecessors of the Ummah did this. As for asking a deceased person to fulfill a need, that is major polytheism (shirk akbar). And asking a deceased person to supplicate to Allah is an innovation (bid'ah) and misguidance. Regarding the difference between someone near the grave and someone far or absent from it: seeking supplication from a deceased person who is absent is major polytheism (shirk akbar), whereas seeking it from someone near the grave is an innovation (bid'ah) and a means to polytheism.