﴿ كَٱلْمُهْلِ يَغْلِى فِى ٱلْبُطُونِ ﴾

“like molten lead will it boil in the belly,”

Like molten copper that is to say like the dregs of black oil ka’l-muhli is the second predicate it will boil inside the bellies if read taghlī then it is a third predicate; if yaghlī then it is a circumstantial qualifier referring to al-muhl ‘molten copper’