Musnad Ahmad 31:835

Ali ibn Ishaq narrated to us, Abdullah narrated to us, Sa'id ibn Yazid Abu Shuja' informed us, from Abu al-Samh, from Abu al-Haytham, from Abu Sa'id al-Khudri, from the Prophet, peace be upon him, who said regarding: {And they will therein be "kalihun" (grimacing/distorted)} [Al-Mu'minun: 104]: "The Fire distorts them, so his upper lip retracts until it reaches the middle of his head, and his lower lip hangs down until it strikes his navel."