قُلْ هُوَ الَّذِي ذَرَأَكُمْ فِي الاَْرْضِ
...
Say:
"It is He Who has created you on the earth..."
meaning, He has spread and distributed you all throughout the various regions and areas of the earth with your differing languages, colors, shapes, appearances and forms.
...
وَإِلَيْهِ تُحْشَرُونَ
and to Him shall you be gathered.
meaning, you all will come together after this separation and division. He will gather you all just as He separated you and He will bring you back again just as He originated you.
Then while informing of the disbelievers who reject the final return, and doubt concerning its real occurrence, Allah said;
وَيَقُولُونَ مَتَى هَذَا الْوَعْدُ إِن كُنتُمْ صَادِقِينَ