[14].Surah Ibrahim {A.S} [Abraham (PBUH)]: Ayat 50-51

Ayat 50. Their garments will be of pitch, and fire will cover their faces.

Ayat 51. That Allah may requite each person according to what he has earned. Truly, Allah is Swift at reckoning.

Hazrat Nu`man bin Bashir (May Allah be pleased with them) reported: Messenger of Allah  [SAWW](PBUH) said, "The least tortured man on the Day of Resurrection is one underneath whose feet will be placed two live coal, and his brain will be boiling, and he would think that he is the most tortured, while he is the least tortured",

[Al-Bukhari Vol.8, Chapter 76, Hadith # 566]. 

Lesson : as mentioned above in Surah Ibrahim {A.S} Ayat 50. "and fire will cover their faces". According to the narration in Muslim, the straps of shoes to be worn by the inhabitants of Hell would be of fire which will make their brains boil like a cooker placed on oven.