[The Wisdom in Making Slaughter and Sacrifice among the Acts of Worship and Rites of Ḥajj]

Answer — and Allah knows best: The secret in that lies in the benefits that result from it, among which, as it appears to me, are the following:
1. Manifesting the glorification of Allah the Exalted through slaughter for Him. This is indicated by His saying: “Neither their flesh nor their blood reaches Allah, but what reaches Him is piety from you…” [Al-Ḥajj:37]
2. Manifesting the oneness of Allah the Exalted, mentioning His Name, and proclaiming His greatness at the time of slaughter.
3. Feeding the poor and the needy, and all the pilgrims, with meat; for they are the guests of the Most Merciful, and guests have a right to hospitality. This is indicated by what has been narrated from the Prophet (May Allah bless him and his family and grant them peace) that he forbade fasting during the Days of Tashrīq and said: “Indeed, they are days of eating, drinking, and marital relations.”

Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.3