Sayyiduna Abu Sa'id Khudri (may Allah be pleased with him) narrates: I heard the Prophet (peace and blessings of Allah be upon him) say: "Gog and Magog will be released, and they will come out upon the people, as Allah Almighty has said: 'And they will descend from every height swiftly.' Muslims will retreat to their cities and fortresses to protect themselves from them. They (Gog and Magog) will bring their livestock with them (when Muslims take their livestock with them to the fortresses), they (i.e., Gog and Magog) will drink all the water of the earth, so much so that if one of them passes by a river, he will say, 'Did there ever use to be water here?' Until every person among the people will be inside a fortress or city, one of them will say, 'We have finished with the people of the earth, now only those in the sky remain.' Then one of them will wave his spear towards the sky, and it will come back with blood on it. This will be as a trial and tribulation. While they are in this state, Allah Almighty will create a worm in their necks, which will be like the nighaf (a worm that appears in the noses of camels and goats). It will come out in their necks, and by morning they will all be dead, so much so that not a sound will be heard from them. The Muslims will say, 'Is there anyone who will risk his life for us and find out what has happened to this enemy?' So one person among them will separate himself for this task, preparing himself for the possibility of being killed. Then he will find that they are all dead, lying one upon another. He will call out: 'O group of Muslims! Rejoice! Glad tidings to you! Allah Almighty has sufficed you against your enemy.' So the people will come out of their cities and fortresses and will release their livestock."