Fighting for the Cause of Allah (Jihaad)
Bukhari :: Book 4 :: Volume 52 :: Hadith 69
Narrated Anas bin Malik:
For thirty days Allah's Apostle invoked Allah to curse those who had killed the companions of Bir-Mauna; he invoked evil upon the tribes of Ral, Dhakwan, and Usaiya who disobeyed Allah and His Apostle. There was reveled about those who were killed at Bir-Mauna a Quranic Verse we used to recite, but it was cancelled later on. The Verse was:
"Inform our people that we have met our Lord. He is pleased with us and He has made us pleased"