﴿ فَلَمْ يَكُ يَنفَعُهُمْ إِيمَٰنُهُمْ لَمَّا رَأَوْا۟ بَأْسَنَا ۖ سُنَّتَ ٱللَّهِ ٱلَّتِى قَدْ خَلَتْ فِى عِبَادِهِۦ ۖ وَخَسِرَ هُنَالِكَ ٱلْكَٰفِرُونَ ﴾

“But their attaining to faith after they had beheld Our punishment could not possibly benefit them such being the way of God that has always obtained for His creatures -: and so, then and there, lost were they who had denied the truth.”

But their faith was of no benefit to them when they saw Our doom — This is God’s way sunnata’Llāhi is in the accusative because it functions as a verbal noun from an implicit verb of the same expression with the believers among all communities which is that faith is of no benefit to them once the chastisement has been sent down which has its precdent; and it is thence that the disbelievers will be losers — it is thence that their status as losers will become apparent to all of mankind even though they will have always been losers before that.