Sahih Al Bukhari Hadith Number 2317

Narrated `Aisha: I twisted the garlands of the Hadis (i.e. animals for sacrifice) of Allah’s Messenger (peace be upon him) with my own hands. Then Allah’s Messenger (peace be upon him) put them around their necks with his own hands, and sent them with my father (to Mecca). Nothing legal was regarded illegal for Allah’s Messenger (peace be upon him) till the animals were slaughtered.

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Hadith number 2317
Volume no 3
Chapter: 14 (To depute someone to sacrifice Budn (camels for sacrifice) and to look after them)