يَسْتَعْجِلُ بِهَا الَّذِينَ لَا يُوْمِنُونَ بِهَا
Those who believe not therein seek to hasten it,
means, they say, `when will this promise be fulfilled, if you are telling the truth' But they say this by way of disbelief and stubbornness, thinking that it is unlikely to happen.
وَالَّذِينَ امَنُوا مُشْفِقُونَ مِنْهَا
while those who believe are fearful of it,
means, they are afraid of it happening.
وَيَعْلَمُونَ أَنَّهَا الْحَقُّ
and know that it is the very truth.
means, that it will undoubtedly come to pass, so they prepare themselves for it and strive for its sake.
It was reported through various chains of narration, a number reaching the level of being Mutawatir, in Sahih and Hasan narrations, in the Books of Sunan and Musnad.
According to some versions, a man addressed the Messenger of Allah in a loud voice, when he was on one of his journeys,
calling out to him, "O Muhammad!"
The Messenger of Allah replied in a similar manner, "Here I am!"
The man said, "When will the Hour come?"
The Messenger of Allah said,
وَيْحَكَ إِنَّهَا كَايِنَةٌ فَمَا أَعْدَدْتَ لَهَا
Woe to you! It will most certainly come. What have you done to prepare for it?
He said, "Love for Allah and His Messenger."
He said;
أَنْتَ مَعَ مَنْ أَحْبَبْت
You will be with those whom you love.
According to another Hadith;
الْمَرْءُ مَعَ مَنْ أَحَب
A man will be with those whom he loves.
This is Mutawatir beyond a doubt. The point is that he did not answer his question about when the Hour would happen, but he commanded him to prepare for it.
أَلَا إِنَّ الَّذِينَ يُمَارُونَ فِي السَّاعَةِ
Verily, those who dispute concerning the Hour,
means, who dispute whether it will happen and think it is unlikely ever to come,
لَفِي ضَلَلٍ بَعِيدٍ
are certainly in error far away.
means, they are clearly ignorant, because the One Who created the heavens and the earth is even more able to give life to the dead, as Allah says;
وَهُوَ الَّذِى يَبْدَأُ الْخَلْقَ ثُمَّ يُعِيدُهُ وَهُوَ أَهْوَنُ عَلَيْهِ
And He it is Who originates the creation, then He will repeat it; and this is easier for Him. (30;27)