time known only to Allah

يَسْـَٔلُونَكَ عَنِ ٱلسَّاعَةِ أَيَّانَ مُرْسَىٰهَا ۖ قُلْ إِنَّمَا عِلْمُهَا عِندَ رَبِّى ۖ لَا يُجَلِّيهَا لِوَقْتِهَآ إِلَّا هُوَ ۚ ثَقُلَتْ فِى ٱلسَّمَـٰوَٰتِ وَٱلْأَرْضِ ۚ لَا تَأْتِيكُمْ إِلَّا بَغْتَةً ۗ يَسْـَٔلُونَكَ كَأَنَّكَ حَفِىٌّ عَنْهَا ۖ قُلْ إِنَّمَا عِلْمُهَا عِندَ ٱللَّهِ وَلَـٰكِنَّ أَكْثَرَ ٱلنَّاسِ لَا يَعْلَمُونَ

They ask you [Prophet] about the Hour, ‘When will it happen?’ Say, ‘My Lord alone has knowledge of it: He alone will reveal when its time will come, a time that is momentous in both the heavens and earth. All too suddenly it will come upon you.’ They ask you about it as if you were eager [to find out]. Say, ‘God alone has knowledge of [when it will come], though most people do not realize it.’