[15].Surah Al-Hjir [The Rocky Tract]: Ayat 7-8

Ayat 7. (and those people who disobey say) "Why do you not bring angels to us if you are of the truthful ones?"

Ayat 8. We send not the angels down except with the truth (i.e. for torment, etc.), and in that case, they (the disbelievers) would have no respite! 

Hazrat Anas bin Malik (May Allah be pleased with him) said: The Messenger of Allah  [SAWW](PBUH) said, "There will be no land which will not be trampled by Dajjal (the Antichrist) but Makkah and Al-Madinah; and there will be no passage leading to them which will not be guarded by the angels, arranged in rows. Dajjal will appear in a barren place adjacent to Al-Madinah and the city will be shaken three times. Allah will expel from it every disbeliever and hypocrite.'' [Muslim Book 41, Chapter 22, Hadith # 7032]. 

Lesson : as mentioned above in Surah Al-Hjir Ayat 08. "We send not the angels down except with the truth" In this narration we find the evil description of a Dajjal and his power of destructing the world expect Makkah and Medina which will be guarded by angels sent by specially by Allah (SWT) to protect the Harmain.