Word by Word Analysis

فَإِن لَّمْ تَفْعَلُوا۟ وَلَن تَفْعَلُوا۟ فَٱتَّقُوا۟ ٱلنَّارَ ٱلَّتِى وَقُودُهَا ٱلنَّاسُ وَٱلْحِجَارَةُ ۖ أُعِدَّتْ لِلْكَـٰفِرِينَ 24

But if you do not - and you will never be able to - then fear the Fire, whose fuel is people and stones, prepared for the disbelievers.