The Ruling on Animals Slaughtered Beside Graves
Question :
There are people who slaughter animals beside the grave of one who has died in their country in the past. They say, according to their belief, that he is a Wali of Allah, so- and-so, the son of so-and-so. They may also allot portion of their income or their cultivation for them. By these actions they intend to seek blessings, to remove afflictions from their dependants, and to seek what is beneficial for them in their livelihood.
Answer:
Slaughtering beside graves, designating a certain place for slaughtering, and allocating some of one's cultivation to be eaten there all of these belong to those deeds which Islam has forbidden and which are considered major Shirk. This is the case if the intent is to seek closeness to the Wali or some other created being, hoping to gain some benefit or repel some harm, or hoping for intercession with Allah or other such things which grave worshippers intend.
Source:
The Permanent Committee
Fatawa Islamiyah, Vol. 6 Page 275