سَأُصْلِيهِ سَقَرَ
Sa usleehi saqar
I will throw him into the scorching Fire.
I will cast him into saqar.
Saqar is a proper name, and it occurs just four times: three of them in this surah, and once in al-Qamar, where it is something tasted. Here the name is given and the line immediately after asks what it is, a formula held for terms a listener cannot be assumed to know already. What follows makes the fire the subject of its own verbs, acting rather than being described.