Musannaf Ibn Abi Shayba 35:8

Ubayd Allah ibn Musa narrated to us, from Isra'il, from Ash'ath ibn Abi al-Sha'tha', from Ja'far ibn Abi Thawr, from Jabir ibn Samurah, who said: The Prophet, may Allah bless him and grant him peace, commanded us to perform ablution after eating camel meat, and not to perform ablution after eating mutton. And he commanded us to pray in sheep pens, and not to pray in camel resting places.