Musnad Abu Ya'la al-Mawsili 42:171

'Uqbah narrated to us, Yunus narrated to us, Muhammad bin Ishaq narrated to us, from 'Asim bin 'Umar bin Qatadah, from Mahmud bin Labid, from Abu Sa'id al-Khudri, that the Messenger of Allah (ﷺ) said: "Yajuj and Majuj (Gog and Magog) will emerge, and they will emerge as Allah said: 'From every elevation they will descend' (Al-Anbiya: 96). They will overwhelm the earth, and the Muslims will retreat from them until the remainder of the Muslims are in their cities and their fortresses, and they will gather their livestock to them. Indeed, the first of them will pass by a river and drink it until they leave nothing in it. Then the last of them will pass in their tracks and one of them will say: 'There was water here once.' Then they will appear over the earth, and one of them will say: 'These are the people of the earth; we have finished them off. Let us fight the people of the heaven.' One of them will shake his spear and throw it toward the heaven, and it will return stained with blood. They will say: 'We have killed the people of the heaven.' While they are like that, Allah will send upon them creatures like the larvae of locusts, which will seize them by their necks, and they will die like the death of locusts, piling upon one another. The Muslims will wake up and not hear a sound from them. They will say: 'Who will buy his soul [risk his life] to see what they have done?' A man among them will say—having prepared himself for the fact that they might kill him—and he will find them dead. He will call out to them: 'Rejoice, for Allah has destroyed your enemy!' Then the people will emerge and release their livestock, and they will have no pasture other than their [the invaders'] flesh, and they will grow fat from it as well as they ever grew from any vegetation they had ever encountered."