﴿ يَسْـَٔلُونَكَ عَنِ ٱلسَّاعَةِ أَيَّانَ مُرْسَىٰهَا ۖ قُلْ إِنَّمَا عِلْمُهَا عِندَ رَبِّى ۖ لَا يُجَلِّيهَا لِوَقْتِهَآ إِلَّا هُوَ ۚ ثَقُلَتْ فِى ٱلسَّمَٰوَٰتِ وَٱلْأَرْضِ ۚ لَا تَأْتِيكُمْ إِلَّا بَغْتَةًۭ ۗ يَسْـَٔلُونَكَ كَأَنَّكَ حَفِىٌّ عَنْهَا ۖ قُلْ إِنَّمَا عِلْمُهَا عِندَ ٱللَّهِ وَلَٰكِنَّ أَكْثَرَ ٱلنَّاسِ لَا يَعْلَمُونَ ﴾

“THEY WILL ASK thee [O Prophet] about the Last Hour: "When will it come to pass?" Say: "Verily, knowledge thereof rests with my Sustainer alone. None but He will reveal it in its time. Heavily will it weigh on the heavens and the earth; [and] it will not fall upon you otherwise than of a sudden." They will ask thee - as if thou couldst gain insight into this [mystery] by dint of persistent inquiry! Say: "Knowledge thereof rests with my Sustainer alone; but [of this] most people are unaware."”

‘On which day will Doomsday occur?’ Questions of this sort are produced by non-serious minds. Only the sincere will believe in the Day of Judgement, without wanting to know the exact date of its occurrence. As this world is a place of testing, Doomsday will be indicated here in terms of caution and warning alone.