﴿ أَوَلَمْ يَنظُرُوا۟ فِى مَلَكُوتِ ٱلسَّمَٰوَٰتِ وَٱلْأَرْضِ وَمَا خَلَقَ ٱللَّهُ مِن شَىْءٍۢ وَأَنْ عَسَىٰٓ أَن يَكُونَ قَدِ ٱقْتَرَبَ أَجَلُهُمْ ۖ فَبِأَىِّ حَدِيثٍۭ بَعْدَهُۥ يُؤْمِنُونَ ﴾

“Have they, then, never considered [God's] mighty dominion over the heavens and the earth, and all the things that God has created, and [asked themselves] whether, perchance, the end of their own term might already have drawn nigh? In what other tiding, then, will they, after this, believe?”

‘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.