Sahih Al Bukhari Hadith Number 1811

Narrated Al-Miswar: Allah’s Messenger (peace be upon him) slaughtered (the Hadi) before he had his head shaved and then he ordered his Companions to do the same.

27  Pilgrims Prevented from Completing the Pilgrimage
Hadith number 1811
Volume no 3
Chapter: 3 (The slaughtering before shaving the head (in case) one is prevented)