Musnad Ahmad 535:10

Musa ibn Dawud and Hasan ibn Musa narrated to us, they said: Ibn Lahi'ah narrated to us, from Darraj. Musa said in his narration: I heard Abdullah ibn al-Harith ibn Juz' al-Zubaydi say: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, in the Fire are snakes like the necks of Bactrian camels; one of them bites a bite, and one finds its heat for forty autumns. And indeed, in the Fire are scorpions like saddled mules; one of them bites a bite, and one finds its heat for forty years."