It has been narrated from Imam Ja’far-as-Sadiq (a.s.) that the Holy Prophet (s.a.w.s.) said,
“On the night of my ascension (Me’raj) when I reached the first heaven, I saw all the Angels rejoicing, but one of them was quite different from the others. His face was fearful and showed signs of anger. He saluted me but unlike others did not smile at me. I asked Jibra’eel as to who he was. Jibra’eel replied, “Verily You should fear him, for we all fear him. This Angel is the keeper of hell. From the day Allah appointed him as the keeper of hell his anger and wrath increases for Allah’s enemies. And when Allah shall order him to take revenge upon His enemies, he shall do so with harshness and severity. If he had ever met anyone joyously, he would also have smiled at you.” I saluted that Angel and he answered me and gave me good news of Paradise.
Then I told Jibra’eel, “O Jibra’eel! tell him to let me have a glimpse of hell.” Jibra’eel requested him and he lifted the veil off and opened one of the doors of hell. Suddenly flames of fire erupted from it which reached the sky and covered it entirely, and started roaring and raging and creating terror. I told Jibra’eel to request him to put backthe veil. The keeper of hell ordered the flames which had reached the sky to go down.”