Abu Dawud Book 1, Hadith Number 185.

Chapter : Performing ablution after touching the flesh of an animal or washing it is not necessary.

Narated By Abu Sa’id al-Khudri : The Prophet (PBUH) passed by a boy who was skinning a goat. The Messenger of Allah (PBUH) said: Give it up until I show you. He (the Prophet) inserted his hand between the skin and the flesh until it reached the armpit. He then went away and led the people in prayer and he did not perform ablution. The version of Amr added that he did not touch water.

Abu Dawud said: This tradition has been narrated through another chain of transmitters, making no mention of Abu Sa’id.