ARRIVAL OF IMAM MAHDI ALAI SALAM?

There is not direct reference in the Quran,only in the hadiths.In most traditions,the IMAM ALI SALAM will arrive with jesus(isa) to defeat the dajjal("the false messiah").Although the concent of mahdi alai salam is not essential doctorine only in sunni muslim, but both sunni and shia muslim,both will agree with him for justice and ruling again in the world.