﴿ وَيَسْتَعْجِلُونَكَ بِٱلْعَذَابِ وَلَن يُخْلِفَ ٱللَّهُ وَعْدَهُۥ ۚ وَإِنَّ يَوْمًا عِندَ رَبِّكَ كَأَلْفِ سَنَةٍۢ مِّمَّا تَعُدُّونَ ﴾

“And [so, O Muhammad,] they challenge thee to hasten the coming upon them of [God’s] chastisement: but God never fails to fulfill His promise - and, behold, in thy Sustainer’s sight a day is like a thousand years of your reckoning.”

And they ask you to hasten the chastisement even though God would never break His promise of sending down the chastisement upon them — and so He sent it down on the day of Badr. And truly a day with your Lord of the days of the Hereafter on account of the severity of the chastisement is like a thousand years of your counting read ta‘uddūna or ya‘uddūna ‘their counting’ in this world.