Tafsir of Al-Qalam 68:16

We shall brand him on the snout! Ibn Jarir said, "We will make his matter clear and evident so that they will know him and he will not be hidden from them, just as the branding mark on the snouts (of animals).'' Others have said,

سنسمه

(We shall brand him), This is the mark of the people of the Hell-fire; meaning, `We will blacken his face on the Day of Judgement,' and the face has been referred to here as snout