"(They will think) that there will be done to them a Faqirah," meaning a catastrophe and an evil.
Muhammad said: "Faqirah"—it is said that it comes from the vertebrae (faqar) of the back, as if it breaks it. You say: "Faqartu al-rajul" (I broke the man's back) when you break his vertebrae.
﴿تظن﴾ تَعْلَمُ ﴿أَنْ يُفْعَلَ بِهَا فَاقِرَةٌ﴾ أَيْ: داهيةٌ وشَرٌّ.
قَالَ محمدٌ: (فاقرة) يُقَالُ: إِنَّهَا مِنْ فقَار الظَّهْر كَأَنَّهَا تكسِره، تَقُولُ: فَقَرْتُ الرَّجُلَ؛ إِذا كَسَرْتَ فَقَارَهُ
