And the Day those who disbelieved are exposed to the Fire [it will be said], "Is this not the truth?" They will say, "Yes, by our Lord." He will say, "Then taste the punishment for what you used to deny."
(Therefore be patient as did those of determination among the Messengers.) meaning, as they were patient with their people's rejection of them. "Those of determination" among the Messengers are Nuh, Ibrahim, Musa, `Isa and the last of all of the Prophets, Muhammad ﷺ. Allah has specifically mentioned their names in two Ayat: Surat Al-Ahzab (33:7) and Surat Ash-Shura (42:13).
وَلاَ تَسْتَعْجِل لَّهُمْ
(and be in no hurry for them.) which means, `do not rush the punishment for them.' This is similar to Allah's saying:
یغْفِرْ لَكُم مِّن ذُنُوبِكُمْ (will forgive your sins for you,) The word 'min' used in the text gives the sense of 'some'. If it is taken in this sense here, it would mean that 'some sins' will be forgiven by embracing Islam. It will indicate that only sins relating to the rights of Allah would be forgiven but not the rights of people. But some exegetes have taken 'min' in this verse as an extra word that has no additional meaning in Arabic idioms. Given this interpretation, no explanation is required.
Tazkirul Quran
Maulana Wahiduddin Khan
The coming into existence of the gigantic universe consisting of the heavens and the earth and then its functioning for millions of years in perfect harmony and with total precision proves that the Creator of this universe is the possessor of immense powers. Moreover, bringing the universe into existence did not exhaust His resources. Had the work of creation been fatiguing for Him, the universe after creation would not have been found running with such great exactitude. The immense power of God being demonstrated throughout the universe suffices for us to be certain that the resurrection of human beings and the taking stock of their deeds is not at all difficult for Him. In the present world reality comes before a man, but he does not accept it. This is because the result of the denial of reality is not immediately obvious. In the Hereafter, the terrible consequences will be there before every man; he will then become extremely serious and will readily accept the reality which he was not prepared to accept in the present world. However, acceptance of truth at that time will be of no avail.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.