Musnad Ahmad 30:3407

Yazid narrated to us, Muhammad informed us, from Abu Salamah, from Abu Hurairah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "The Fire complained to its Lord, the Mighty and Majestic, and said: 'Some parts of me are consuming others.' So He permitted it two breaths: one in the winter and one in the summer. The most intense heat you find is from its heat, and the most intense cold you find is its *zamharir* (bitter cold)."