Narrated Anas ibn Malik: The Prophet ﷺ said: There is no slaughtering (at the grave) in Islam. Abd al-Razzaq said: They used to slaughter cows or sheep at grave.
Explanation & Benefits
Shaykh Umar Farooq Saeedi
Benefits and Issues:
This was a custom from the Age of Ignorance (Jahiliyyah), as if the deceased was very generous during his lifetime. So his relatives, after his death, would slaughter an animal at his grave and leave it there for animals to eat. Islam has prohibited this act. Now, to slaughter an animal at a grave for any intention, to offer votive offerings, or to cook pots of food and distribute them is forbidden (haram).
Source: Sunan Abu Dawood – Commentary by Shaykh Umar Farooq Saeedi, Page: 3222