جامع الترمذي

Narrated Abu Rafi': a Hadith of Abu Hurairah, from the Prophet (ﷺ), regarding the 'barrier (18:93).' "They excavated each day, until when they are just about to penetrate it, their leader says: 'Go back so that you can penetrate it tomorrow!'" He said: "But Allah makes it return just as it was, until their appointed time, when Allah ordains to send them upon the people, and their leader says: 'Go back so you can penetrate it tomorrow, if Allah wills.' So he makes this exception." He said: "So they return, and find it just as it was when they left it. Then they penetrate it, and [they (Ya'juj & Ma'juj)] are released upon the people drinking up the water, and the people flee from them. They shoot their arrows into the heavens so they returned dyed with blood, and they say - crudely and arrogantly - 'We vanquished those in the earth, let us dominate the inhabitants of the heavens.' Then Allah sends Naghaf upon them, attaching to the nape of their necks, destroying them." He said: "By the One in Whose Hand is the soul of Muhammad! The beasts of the earth will become very fat and bloated with milk from their flesh."