Question 267: Some people invoke the dead when visiting the graves of Al-Baqee` and ‘Uhud and throw money there for their sake. What is the ruling on this practice?
Answer: Invoking the dead and appealing to them for help when visiting their graves is regarded as a form of major Shirk (associating others with Allaah in His Divinity or worship that takes the Muslim out of Islaam) which draws a person out of the religion of Islaam. This is because supplication is the highest kind of all acts of worship. Allaah (Exalted be He) says, And whoever invokes (or worships), besides Allaah, any other ilaah (god), of whom he has no proof; then his reckoning is only with his Lord. Surely! Al-Kaafiroon (the disbelievers in Allaah and in the Oneness of Allaah, polytheists, pagans, idolaters) will not be successful. Also, throwing money on the graves of the dead and offering sacrifices for their sake are the worst types of major Shirk... read more here.