Hazrat Hudaifa relates: "The Messenger of Allah (saas) rose one day; he described us the things that would take place up until the Day of Reckoning.Some remembered, and others forgot. These friends of mine wil know. The things that Rasulullah (saas) spoke of and that I have gradually forgotten, I remember when they take place. In the same way that one does not call to mind someone in their absence, but one recognized them when one sees them..." (Tirmidhi, Kitab al-Fitan: 23)
He also said: “Rasulullah (saas) told me what would happen up to the Day of Reckoning. I asked him about everything that would happen to him. I asked him about all that would happen, not only what would take out the people of Madina. (Muslim, Kitab al-Fitan Wa Ashrat as-Sa’ah (18/16 Nawawi Commentary)
Abu Zayd Amr ibn Ahtab al-Ansari (ra) said: “Rasulullah (saas) rose to the pulpit after leading us in the morning prayer, preached until noon and then descended. He prayed. He then rose to the pulpit again. He preached until sunset. He told us what had happened and would happen in the future. Those of us who know this best are those best capable of memorizing.” (Muslim, Kitab al-Fitan Wa Ashrat as-Sa’ah (18/16 Nawawi Commentary)
OUR PROPHET (SAAS) DESCRIBED THE PROPHET JESUS (AS) AND HAZRAT MAHDI (AS) IN GREAT DETAIL FOR US TO RECOGNIZE THEM WHEN THEY COME, AND SAID I HAVE DESCRIBED THEM SO YOU WILL RECOGNIZE THEM
Abu Huraira narrated, "The Prophet (saas) said:
'There is no prophet between me and him, that is, Jesus, peace be upon him. He will descend (to the earth).
WHEN YOU SEE HIM, RECOGNIZE HIM:
A man of medium height, reddish hair,
wearing two light yellow garments,
looking as if drops were falling down from his head though it will not be wet.
He will fight the people for the cause of Islam [struggle intellectually].
He will break the cross [annul the worship of the cross],
kill the pig [inform that eating pork is forbidden],
and abolish the jizyah.
He will destroy the antichrist [make him ineffective] and will live on the earth for forty years and then he will die. The Muslims will pray over him.'" (Abu Dawud)
Believers will recognize the dajjal (antichrist) when they see him, because our Prophet (saas) has described him in detail
When one sees him, HE WILL RECOGNIZE HIM BECAUSE HE APPEARS AS DESCRIBED BY RASULULLAH (SAAS) and he will cry out: «O People ! This is the dajjal described by Rasulullah (saas)!»