it was said to comfort him: وَلَقَدِ اسْتُهْزِئَ بِرُسُلٍ مِّن قَبْلِكَ فَأَمْلَيْتُ لِلَّذِينَ كَفَرُوا ثُمَّ أَخَذْتُهُمْ ۖ فَكَيْفَ كَانَ عِقَابِ (And Messengers have been mocked at before you, so I let the disbelievers go on for a while. Then I seized them. So, how was My punishment?) In other words, it means that conditions faced by the Holy Prophet were not faced by him alone. There were prophets before him who had been facing similar conditions when their deniers were not seized immediately upon the commitment of their crime and they continued to make fun of the prophets. When they reached the limit, they were seized by Divine punishment and what a seizure that was which left none of them active enough to go on with their confrontation.
Allah says to His Messenger, while comforting him in facing his people's denial of him,
`(And indeed (many) Messengers were mocked at before you), so you have a good example in them,
(but I granted respite to those who disbelieved,) deferred their judgment for a term appointed,
(and finally I punished them.) with encompassing punishment. How did you obtain the news of how I gave them respite and then took them with punishment' Allah said in another Ayah,
(And many a township did I give respite while it was given to wrongdoing. Then (in the end) I seized it (with punishment). And to Me is the (final) return (of all).)22:48 It is recorded in the Two Sahihs that the Prophet said,
(Verily, Allah gives respite to the unjust until when He seizes him, He never lets go of him.) The Messenger next recited this Ayah,
(Such is the punishment of your Lord when He seizes the (population of) towns while they are doing wrong. Verily, His punishment is painful, (and) severe.)11:102