Sahih Bukhari
Fighting for the Cause of Allah (Jihaad)
Volume: 004 / Book Number: 052 / Hadith Number: 249
Narrated Abu Bashir Al-Ansari:
That he was in the company of Allah's Apostle on some of his journeys. (The sub-narrator 'Abdullah adds, "I think that Abu Bashir also said, 'And the people were at their sleeping places.") Allah's Apostle sent a messenger ordering: "There shall not remain any necklace of string or any other kind of necklace round the necks of camels except it is cut off."