Surah 15. Al-Hijr, Ayah 57

When cordial understanding was established between Abraham and his guests and probably when the guests were about to depart, Abraham put a question to them: "What is the mission on which you are going?" It was further implied: "Is there anything I can do to help?" But no. The mission was one of Punishment for abominable sins. Note that the mention of Allah's Wrath is always linked with that of Allah's Mercy, and the Mercy comes first. The same angels that came to punish Sodom and Gomorrah were charged first to give the good news of Allah's Mercy to Abraham in the shape of a long line of Teachers of Righteousness.