Ali bin Ms'hr علي بن مسهر · The Book on Sacrifices

That the Messenger of Allah (ﷺ) said: "A human does no action from the actions on the day of Nahr more beloved to Allah then spilling blood (of sacrificial animals). On the Day of Judgement, it will appear with its horns, and hair, and hooves, and indeed the blood will be accepted by Allah from where it is received before it even falls upon earth, so let your heart delight in it."