The Muslims are agreed that it is prescribed to offer a sacrifice (udhiyah), and it is permissible to offer a sacrifice on behalf of one who has died, because of the general meaning of the hadeeth of the Prophet (peace and blessings of Allaah be upon him), When the son of Adam dies, all his good deeds come to an end except three: ongoing charity, beneficial knowledge, or a righteous son who will pray for him. Narrated by Muslim. Abu Dawood, al-Tirmidhi and al-Nasaa'i, and by al-Bukhaari in al-Adab al-Mufrad from Abu Hurayrah. Slaughtering a sacrifice on his behalf is a kind of ongoing charity, because it benefits the person offering the sacrifice, the deceased person, and others.
And Allaah is the Source of strength.
Reproduced from Islam QA