It is narrated from Sayyiduna Uqbah bin Amir (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "On the Day of Resurrection the sun will come close to the earth, and people will sweat. The sweat of some people will reach their ankles, of some halfway up the shin, of some their knees, of some their buttocks, of some their waist, of some their shoulders, of some their throat, and some will be bridled by it up to the mouth." And the Messenger of Allah (peace and blessings be upon him) gestured, gathering his fingers between his two lips, then said: "And some will be completely submerged by it."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 14905