فَوَيْلٌ لِّلْمُصَلِّينَ
So woe to those who pray— (107:4)
الَّذِينَ هُمْ عَن صَلَاتِهِمْ سَاهُونَ
those who are heedless of their prayers. (107:5)
Read alone, verse 4 could be mistaken for an undifferentiated condemnation of all worshippers. Verse 5 qualifies the class under warning. The condemnation falls on those described by negligence, not on everyone who performs prayer.
The sharp opening creates concern, while the dependent description completes the intended scope. Verse division must not be confused with the end of a semantic unit.