(Ar-Room) 30 : 6
وَعْدَ اللَّهِ ۖ لَا يُخْلِفُ اللَّهُ وَعْدَهُ وَلَٰكِنَّ أَكْثَرَ النَّاسِ لَا يَعْلَمُونَ
It is the Promise of Lord Allah; Allah doesn’t fail in His Promise, but most of mankind are not having the Knowledge.
The Promise and Knowledge mentioned in the verse are Adhikr. Only the one in a thousand who testifies Adhikr will have Confirmed belief in His verses. All other nine hundred and ninety-nineFujjar who falsify the Mercy Adhikr will have neverending doubt concerning every matter and they are destined into Hell as explained in verses 11: 118-119 and 15: 44. See explanation 3: 194; 8: 48 and 11: 17.