[Sahih Bukhari: Volume 4, Book 52, Number 260]
Narrated Ikrima (Radi Allah Anhu): Ali (Radi Allah Anhu) burnt some people and this news reached Ibn ‘Abbas (Radi Allah Anhu), who said, “Had I been in his place I would not have burnt them, as the Prophet (sal-allahu-alleihi-wasallam) said, ‘Don’t punish (anybody) with Allah’s Punishment.’ No doubt, I would have killed them, for the Prophet said, ‘If somebody (a Muslim) discards his religion, kill him.’ “
[Sahih Bukhari: Volume 4, Book 54, Number 536]
Narrated Abu Huraira (Radi Allah Anhu): I heard Allah’s Messenger saying, “An ant bit a Prophet amongst the Prophets, and he ordered that the place of ants be burnt. So, Allah inspired to him, ‘It is because one ant bit you that you burnt a nation amongst the nations of that glorify Allah?’ “