Concerning Allah's statement,

فَلَا تَعْجَلْ عَلَيْهِمْ ...

So make no haste against them; We only count out to them a (limited) number.

This means, "Do not be hasty with the punishment that is going to befall them, O Muhammad.''

... إِنَّمَا نَعُدُّ لَهُمْ عَدًّا ﴿٨٤﴾

We only count out to them a number.

This means, "We are only delaying them for a fixed appointment whose time is numbered. They are destined for that and there is no escaping the torment of Allah and His exemplary punishment.''

Allah says,

وَلاَ تَحْسَبَنَّ اللَّهَ غَـفِلاً عَمَّا يَعْمَلُ الظَّـلِمُونَ

And consider not that Allah is unaware of that which the wrongdoers do. (14:42)

And He says,

فَمَهِّلِ الْكَـفِرِينَ أَمْهِلْهُمْ رُوَيْداً

So give a respite to the disbelievers; deal gently with them for a while. (86:17)

And Allah says,

إِنَّمَا نُمْلِى لَهُمْ لِيَزْدَادُواْ إِثْمَاً

We postpone the punishment only so that they may increase in sinfulness. (3:178)

نُمَتِّعُهُمْ قَلِيلاً ثُمَّ نَضْطَرُّهُمْ إِلَى عَذَابٍ غَلِيظٍ

We let them enjoy for a little while, then in the end We shall oblige them to (enter) a great torment. (31:24)

قُلْ تَمَتَّعُواْ فَإِنَّ مَصِيرَكُمْ إِلَى النَّارِ

Say: "Enjoy! But certainly, your destination is the (Hell) Fire.'' (14:30)

As-Suddi said, إِنَّمَا نَعُدُّ لَهُمْ عَدًّا (We only count out to them a (limited) number),

means years, months, days and hours.''