Musnad Ahmad 788:221

Muhammad ibn Bishr narrated to us, he said: Sa'id ibn Abi 'Arubah narrated to us, he said: Ghalib al-Tammar narrated to us, from Humayd ibn Hilal, from Masruq ibn Aws, from Abu Musa al-Ash'ari, from the Messenger of Allah (may Allah bless him and grant him peace), that he decreed regarding the fingers: ten [camels] for each one.