وَمَا كَانَ النَّاسُ إِلَّا أُمَّةً وَاحِدَةً فَاخْتَلَفُوا وَلَوْلَا كَلِمَةٌ سَبَقَتْ مِنْ رَبِّكَ لَقُضِيَ بَيْنَهُمْ فِيمَا فِيهِ يَخْتَلِفُونَ ﴿۱۹﴾ وَيَقُولُونَ لَوْلَا أُنْزِلَ عَلَيْهِ آيَةٌ مِنْ رَبِّهِ فَقُلْ إِنَّمَا الْغَيْبُ لِلَّهِ فَانْتَظِرُوا إِنِّي مَعَكُمْ مِنَ الْمُنْتَظِرِينَ ﴿۲۰﴾

﴾19﴿ Wa maa kaanan naasu illaaa ummatanw waahidatan fa khtalafoo; wa law laa kalimatun sabaqat mir Rabbika laqudiya bainahum fee maa feehi yakhtalifoon
﴾20﴿ Wa yaqooloona law laaa unzila 'alaihi aayatun mir Rabbihee faqul innamal ghaibu lillaahi fantaziroo innee ma'akum minal muntazireen

﴾19﴿ And the people were but one community (united upon monotheism), but then they differed. And if it had not been for a decree (of postponing punishment) that had already gone forth from your Lord, it would have been judged between them concerning that in which they differ
﴾20﴿ And they say, Why has no sign been sent down to him from his Lord (that we want), Say, Indeed, the knowledge of the unseen belongs only to Allah. So wait; indeed, I am with you among those who wait

[19] This verse is an answer to a question. The question was: “Perhaps this belief in intercession is forbidden in your religion, but wasn’t it permitted in previous religions?”
The answer is given that the religion of all prophets is one and the same. It was the people who created divisions within it. (Ummatan wāḥidah)—meaning, from the time of Adam (peace be upon him) until the shirk of the people of Nuh (peace be upon him), or from the destruction of the people of Nuh until the people of ‘Ād.
Another question was: “If this belief is truly disbelief and shirk, then why hasn’t punishment descended upon them?”
The answer is in the phrase (wa lawlā kalimah)—meaning, had it not been for a decree. The “word” (kalimah) refers to Allah’s decision that this Ummah will not be destroyed by worldly punishment until the Day of Judgment.
The meaning is that Allah, the Exalted, has decreed not to punish anyone until the message has reached them—either through the Prophet (May Allah bless him and give him peace) or through his representatives.
[20] This verse is a warning regarding the demand for miracles from the Prophet—specifically, the miracles that they desired according to their own wishes.
The essence of the response is: sending down miracles belongs to the realm of the unseen (ghayb), and I do not possess knowledge of the unseen—so how could I have control over bringing miracles?
(Fantaẓirū)—So wait, either for the coming of the sign or for the consequence of your denial.