Dajjal and Jesus 2nd Coming

Islamic traditions believe that at the end of the world, a man by the name of Dajjal will be raised to fight the Believers. Dajjal will raise an army to fight the Moslems. Then God will send down Jesus to Earth, to fight Dajjal and will eventually kill it. The Moslems, led by Imam Mahdi, will defeat Dajjal's forces.

The event of Dajjal and Jesus' second coming were considered the most important event to occur in those last days. They were so important, hundreds of reported hadiths (sayings of the Prophet Muhammad) focus on this subject alone. Surprisingly, however, the Holy Qur'an does not mention these two important events at all.

Aside of natural phenomenons to occur during those last days (earthquakes, the sun falling to Earth, etc), the Holy Qur'an mentions two notable events only, i.e. the emerging of a worm from the Earth and the descend of Gog and Magog from their iron-clad prison. Interestingly, these events are less elaborated and discussed compared to Dajjal and Jesus' second coming.

Now, if the Holy Qur'an does not mention about Dajjal and Jesus' second coming, where do the ideas came from?