Surah Al-Muddaththir 74:29

لَوَّاحَةٌ لِّلْبَشَرِ

Altering [i.e., blackening] the skins.

Translation: Saheeh International

Tafsir

It burns away the flesh scorching the surface of skin.

Excerpt from Tafsir al-Jalalayn, commentary on 74:29, via Quran.com. The reader has the full commentary and 9 more tafsirs.