It is narrated from Sayyiduna Uqbah bin Amir (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Pray in the sheep pens, and do not pray in the camel enclosures or the places where camels kneel."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15009