Tafsir of Al-Kahf 18:99

وتركنا بعضهم

We shall leave some of them, meaning mankind, on that day, the day when the barrier will be breached and these people (Ya'juj and Ma'juj) will come out surging over mankind to destroy their wealth and property

وتركنا بعضهم يوميذ يموج في بعض

We shall leave some of them to surge like waves on one another; As-Suddi said: "That is when they emerge upon the people.'' All of this will happen before the Day of Resurrection and after the Dajjal, as we will explain when discussing the Ayat:

حتى إذا فتحت يٲجوج ومٲجوج وهم من كل حدب ينسلون

واقترب الوعد الحق

Until, when Ya'juj and Ma'juj are let loose, and they swoop down from every Hadab. And the true promise shall draw near... (21:96-97)

ونفخ في الصور

and As-Sur will be blown. As-Sur, as explained in the Hadith, is a horn that is blown into. The one who will blow into it is (the angel) Israfil, peace be upon him, as has been explained in the Hadith quoted at length above, and there are many Hadiths on this topic. According to a Hadith narrated from Atiyah from Ibn Abbas and Abu Sa`id, and attributed to the Prophet,

كيف أنعم وصاحب القرن قد التقم القرن وحنى جبهته واستمع متى يومر

How can I relax when the one with the Horn has put the Horn in his mouth and has knelt down, listening out for the command to be given to him? They said, "What should we say?" He said:

قولوا

حسبنا الله ونعم الوكيل على الله توكلنا

Say: "Allah is Sufficient for us and the best Disposer of affairs, in Allah have we put our trust.''

فجمعناهم جمعا

and We shall collect them (the creatures) all together. means, `We shall bring them all together for Reckoning.'

قل إن اﻻولين واﻻخرين

لمجموعون إلى ميقت يوم معلوم

Say: "(Yes) verily, those of old, and those of later times. All will surely be gathered together for appointed meeting of a known Day. (56:49-50)

وحشرنهم فلم نغادر منهم أحدا

and we shall gather them all together so as to leave not one of them behind. (18:47)