Musnad Ahmad 482:147

Hassan narrated to us, Ibn Lahi'ah narrated to us, Abu 'Ushana Hayy ibn Yu'min al-Ma'afiri narrated to us, that he heard 'Uqbah ibn 'Amir saying: I heard the Messenger of Allah (peace and blessings of Allah be upon him) saying: "The sun will draw near to the earth, and the people will sweat. Among the people are those whose sweat will reach their heels, and among them are those whose sweat will reach the middle of their shins, and among them are those whose sweat will reach their knees, and among them are those whose sweat will reach their buttocks, and among them are those whose sweat will reach their flanks, and among them are those whose sweat will reach their shoulders, and among them are those whose sweat will reach their necks, and among them are those whose sweat will reach the middle of their mouths"—and he gestured with his hand, placing it over his mouth: "I saw the Messenger of Allah (peace and blessings of Allah be upon him) gesturing like this"—"and among them are those whom their sweat will cover." And he struck with his hand as a gesture.