Musnad Ahmad 30:2673

Yazid narrated to us, he said: Muhammad informed us, from Abu al-Zinad, from al-A'raj, from Abu Hurayrah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "A prophet from among the prophets rested under a tree, and an ant stung him. So he ordered his equipment to be removed from under it, then he ordered it [the ant hill] and it was burned with fire. Then Allah, the Almighty and Majestic, revealed to him: 'Why not just one ant?'"