Here Allah consoles His Prophet Muhammad ﷺ for the disbelief of those among his people who opposed him.

وَإِن يُكَذِّبُوكَ فَقَدْ كَذَّبَتْ قَبْلَهُمْ قَوْمُ نُوحٍ

(And if they deny you, so did deny before them the people of Nuh) until His saying,

How the Day of Resurrection will be equal to one thousand years by our reckoning

In this verseإِنَّ يَوْمًا عِندَ رَ‌بِّكَ كَأَلْفِ سَنَةٍ (22:47) means that one day with your Lord is like one thousand years of what you count. This verse can be interpreted in two ways. The first meaning is that the verse refers to the Day of Resurrection and the events which will take place on that day will be so horrifying and of such extreme severity that the day will appear never to end, as if it was equal to one thousand years according to our reckoning. Many commentators have interpreted this verse accordingly.