Is it an act of Shirk (Associating others in worship with Allah) if someone calls and makes Du`a' (supplication) to the Prophet (peace be upon him) near his grave or far from it
to fulfill their needs or seek his help when calamities and misfortunes afflict them?
If someone makes Du`a' to the Prophet (peace be upon him) after his death to fulfill their needs or seeks his help to remove distress, they are committing an act of Al-Shirk-ul-Akbar (major form of associating others in worship with Allah) which will take them outside the fold of Islam. There is no difference whether this is done near or far away from the Prophet's grave like saying: "O Messenger of Allah! Cure me," or asking him to return an absent person, and so on, as Allah (Exalted be He) says:
And the mosques are for Allâh (Alone): so invoke not anyone along with Allâh.
Allah (Glorified and Exalted be He) also says:
And whoever invokes (or worships), besides Allâh, any other ilâh (god), of whom he has no proof; then his reckoning is only with his Lord. Surely! Al-Kâfirûn (the disbelievers in Allâh and in the Oneness of Allâh, polytheists, pagans, idolaters) will not be successful.
Furthermore, Allah (Glorified and Exalted be He) says:
Such is Allâh, your Lord; His is the kingdom. And those, whom you invoke or call upon instead of Him, own not even a Qitmîr (the thin membrane over the date-stone).
If you invoke (or call upon) them, they hear not your call; and if (in case) they were to hear, they could not grant it (your request) to you. And on the Day of Resurrection, they will disown your worshipping them. And none can inform you (O Muhammad صلى الله عليه وسلم) like Him Who is the All-Knower (of everything).