Sunan An-Nasai, Chapter: The Book of Purification

that "some people from 'Ukl came to the Messenger of Allah (saw) and spoke about Islam. They said: 'O Messenger of Allah, we are nomads who follow the herds, not farmers and growers, and the climate of Al-Madinah does not suit us.' So the Messenger of Allah (saw) told them to go out to a flock of female camels and drink their milk and urine. When they recovered - and they were in the vicinity of Al-Harrah - they apostatized after having become Muslim, killed the camel-herder of the Messenger of Allah (saw) and drove the camels away. News of that reached the Messenger of Allah (saw) and he sent people after them. They were brought back, their eyes were smoldered with heated nails, their hands and feet cut off, then they were left in Al-Harrah in that state until they died." (Sahih)