From Sahih Bukhari (Hadith 2317):
Narrated `Aisha:I twisted the garlands of the Hadis (i.e. animals for sacrifice) of Allah's Messenger (ﷺ) with my own hands. Then Allah's Messenger (ﷺ) 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 (ﷺ) till the animals were slaughtered
Reference: Bukhari 2317