Musnad Ahmad 907:72

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Simak ibn Harb, from Abu Thawr ibn 'Ikrimah, from his grandfather, who is Jabir ibn Samurah, that the Messenger of Allah (peace and blessings of Allah be upon him) was asked about praying in the resting places of camels? He said: "Do not pray." And he was asked about praying in the resting places of sheep? He said: "Pray." And he was asked about performing ablution (wudu) after eating camel meat? He said: "Perform ablution from it." And he was asked about sheep meat? He said: "If you wish, perform ablution, and if you wish, do not perform ablution."