﴿ فَكَيْفَ إِذَا تَوَفَّتْهُمُ ٱلْمَلَٰٓئِكَةُ يَضْرِبُونَ وُجُوهَهُمْ وَأَدْبَٰرَهُمْ ﴾

“hence, how [will they fare] when the angels gather them in death, striking their faces and their backs?”

Then how will it be their predicament when the angels take them away beating yadribūna is a circumstantial qualifier referring to the angels their faces and their backs? with hooked iron rods.