يَوْمَ يَأْتِ لاَ تَكَلَّمُ نَفْسٌ إِلاَّ بِإِذْنِهِ ...

On the Day when it comes, no person shall speak except by His (Allah's) leave.

This means that on the Day of Judgement no one will speak except with the permission of Allah.

This is similar to another verse, which says,

لاَّ يَتَكَلَّمُونَ إِلاَّ مَنْ أَذِنَ لَهُ الرَّحْمَـنُ وَقَالَ صَوَاباً

they will not speak except him whom the Most Gracious (Allah) allows, and he will speak what is right. (78:38)

Allah also says,

وَخَشَعَتِ الأَصْوَاتُ لِلرَّحْمَـنِ

And all the voices will be humbled for the Most Gracious (Allah). (20:108)

In the Hadith about the intercession, which is recorded in the Two Sahihs, the Messenger of Allah said,

وَلَا يَتَكَلَّمُ يَوْمَئِذٍ إِلَّا الرُّسُلُ، وَدَعْوَى الرُّسُلِ يَوْمَئِذٍ اللَّهُمَّ سَلِّمْ سَلِّم

No one will speak on that day except the Messengers, and the call of the Messengers will be, "O Allah, save us, save us.''

Concerning Allah's statement,

... فَمِنْهُمْ شَقِيٌّ وَسَعِيدٌ ﴿١٠٥﴾

Some among them will be wretched and (others) blessed.

This means that from the people of the gathering (on Judgement Day), some will be miserable and some will be happy.

This is as Allah said,

فَرِيقٌ فِى الْجَنَّةِ وَفَرِيقٌ فِى السَّعِيرِ

When a party will be in Paradise and a party in the blazing Fire. (42:7)

Al-Hafiz Abu Ya`la recorded in his Musnad on the authority of Ibn Umar that Umar said,

"When this verse was revealed, فَمِنْهُمْ شَقِيٌّ وَسَعِيدٌ (Some among them will be wretched and (others) blessed), I asked the Prophet, `O Messenger of Allah, will there be a sign for us to know (which party we are from)? Will it be because of something that a person did, or something that he did not do?'

He said,

عَلَى شَيْءٍ قَدْ فُرِغَ مِنْهُ يَا عُمَرُ وَجَرَتْ بِهِ الْأَقْلَامُ،وَلَكِنْ كُلٌّ مُيَسَّرٌ لِمَا خُلِقَ لَه

O Umar, it will be due to something that he did and the pens wrote it down. But every easy deed was created for its purpose (to be carried out).