Sayyiduna Khabbab (may Allah be pleased with him) said: "The Messenger of Allah (peace and blessings be upon him) sent us on an expedition, and we were overcome by thirst and had no water with us. Then the she-camel of one of us knelt down, and between her legs there was something like a waterskin, so we drank from her milk."
Hadith Referenceالمعجم الكبير للطبراني / باب الخاء / 3682