‘Atā' ibn Yasār and Abu Hurayrah (may Allah be pleased with both of them) reported that the Prophet (may Allah's peace and blessings be upon him) said: "O Allah, do not make my grave an idol that is worshiped. Allah's wrath was intense upon a people who took the graves of their prophets as places of worship."
شرح الحديث :
The Prophet (may Allah's peace and blessings be upon him) feared that his nation would treat his grave in the same way the Jews and Christians treated the graves of their prophets. They exaggerated in venerating them until their prophets' graves became idols. So the Prophet (may Allah's peace and blessings be upon him) supplicated his Lord not to make his grave as such. Then he clarified why the Jews and Christians incurred the wrath and curse (of Allah); it was because of what they did with the graves of their prophets, turning them into worshiped idols. They thus committed polytheism, which is contrary to monotheism.