Question 15: There are many shaykhs in my country who do the following things: They play Duffs (tambourine-like instruments without bells) and go to graves where they slaughter sheep, camels, and cows, and they cook food there. Is this Haraam (prohibited) or not? They have also constructed a dome outside the city where they play Duffs and drums, and shout loudly: “Help us, O our Shaykh Jeelaanee!” They also invoke the help of other shaykhs. In addition to this, they walk among the people collecting money from them, and say that it is to visit Shaykh so-and-so and for other matters. If someone falls ill, they take them to these shaykhs who recite Aayahs (Qur’aanic verses) over them, and ask them to bring a ram, a bull, a camel, or other animals. People pay them large sums of money over the year and they go to them. Are these practices prohibited according to our Deen (religion)?
Answer: It is not permissible to slaughter camels, cows, sheep, or anything else on graves.In fact, it is an act of major Shirk (associating others with Allaah in His Divinity or worship) that puts the doer beyond the pale of Islaam, if by doing so… read more here.