Narrated Abdullah ibn Amr radiallahu anhu:

Once the Prophet peace be upon him remained behind us in a journey. He joined us while we were performing ablution for the prayer which was over-due. We were just passing wet hands over our feet (and not washing them properly) so the Prophet peace be upon him addressed us in a loud voice and said twice or thrice: "Save your heels from the fire."

Narrated Abu Huraira radiallahu anhu:

While the Prophet peace be upon him was saying something in a gathering, a Bedouin came and asked him, "When would the Hour (Doomsday) take place?" Allah's Messenger peace be upon him continued his talk, so some people said that Allah's Messenger peace be upon him had heard the question, but did not like what that Bedouin had asked. Some of them said that Allah's Messenger peace be upon him had not heard it. When the Prophet peace be upon him finished his speech, he said, "Where is the questioner, who inquired about the Hour (Doomsday)?" The Bedouin said, "I am here, O Allah's Apostle." Then the Prophet peace be upon him said, "When honesty is lost, then wait for the Hour (Doomsday)." The Bedouin said, "How will that be lost?" The Prophet peace be upon him said, "When the power or authority comes in the hands of unfit persons, then wait for the Hour (Doomsday.)"