It is narrated from Sayyiduna al-Hasan bin Ali (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) passed by him while he had in his hand a bone with meat on it, which he was gnawing. He said: "The Messenger of Allah (peace and blessings be upon him) took it and bit off some meat from it once or twice, then prayed without performing ablution (wudu)."
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 2703