Sahih Muslim Book 26, Hadith Number 5568.

Chapter : Prohibition of killing the ants.

Abu Huraira reported Allah’s Messenger (may peace be upon him) as saying: An Apostle from amongst the Apostles of Allah encamped under a tree, and an ant bit him, and he commanded his belongings to be removed from underneath the tree. He then commanded and it was burnt, and Allah revealed to bin): “Why one ant (which had bitten you) was not killed?”