(Verily We sent before thee) O Muhammad (messengers to their own folk. They brought them clear proofs (of Allah's Sovereignty)) they explained to them the commands, prohibitions and signs but they did not believe. (Then We took vengeance) by sending a chastisement (upon those who were guilty) the idolaters. (To help believers is incumbent upon Us) it is incumbent to help the believers with the messengers by saving them and destroying their enemies.