Musnad Abu Ya'la al-Mawsili 160:249

Ahmad ibn ‘Isa narrated to us, Ibn Wahb narrated to us, ‘Amr ibn al-Harith narrated to us, that Abu al-Samh narrated to him, from Ibn Hujayrah, from Abu Hurayrah, from the Messenger of Allah (may Allah bless him and grant him peace), that he said: "The believer in his grave is in a garden, and his grave is widened for him seventy cubits, and it is illuminated for him like the moon on the night of the full moon. Do you see regarding what this verse was revealed: 'But whoever turns away from My Reminder - indeed, he will have a depressed [i.e., difficult] life, and We will gather him on the Day of Resurrection blind' [20:124]? Do you know what the 'depressed life' is?" They said, "Allah and His Messenger know best." He said, "It is the punishment of the disbeliever in his grave. By the One in Whose hand is my soul, there are unleashed upon him ninety-nine dragons. Do you know what a dragon is? It is ninety-nine snakes, each snake having seven heads, blowing into his body, stinging him, and scratching him until the Day of Resurrection."