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.
Sunan Abi Dawud Book 21, Hadith 134
← Previous Hadith Whenever the Prophet (ﷺ) became free from burying the dead, he used to stay at him (i.e. his grave) and say: Seek forgiveness for your brother, and beg steadfastness for him, for he will be questioned now.

Abu Dawud said: The full name of the narrator Buhair is Buhair b. Raisan.

Sunan Abi Dawud Book 21, Hadith 133 Next Hadith → One day the Messenger of Allah (ﷺ) went out and prayed over the martyrs of Uhud like his prayer over the dead, and then returned.

Sunan Abi Dawud Book 21, Hadith 135