The Messenger of Allah ﷺ said, "There is no slaughtering at graves in Islam."Abdul-Razzaq explained that they used to slaughter a cow or a sheep at the grave.
حدثنا يحيى بن موسى البلخي حدثنا عبد الرزاق أخبرنا معمر عن ثابت
قال رسول الله ﷺ لا عقر في الإسلام قال عبد الرزاق كانوا يعقرون عند القبر بقرة أو شاة
Its isnad is sahih. Ahmad narrated it: 3/197, from Abdul-Razzaq, and it is in his Musannaf, no. 6690, in full. Ibn Hibban graded it sahih, no. 738.