From Sahih Bukhari (Hadith 1711):
Narrated Nafi`:Ibn `Umar used to send his Hadi from Jam' (to Mina) in the last third of the night with the pilgrims amongst whom there were free men and slaves, till it was taken into the Manhar (slaughtering place) of the Prophet (ﷺ)
Reference: Bukhari 1711