Musnad Abu Ya'la al-Mawsili 115:281

Muhammad ibn Mahdi narrated to us, Abd al-Razzaq narrated to us, Ma'mar informed us, from Qatadah, from Anas, who said: "O mankind, fear your Lord" up to His saying, "but the punishment of Allah is severe" (Surah al-Hajj) was revealed to the Prophet, peace and blessings of Allah be upon him, while he was on a journey. He raised his voice with it until his companions gathered around him. He said: "Do you know what day this is? It is the day when Allah will say to Adam: 'Rise and send forth a contingent to the Fire.' From every thousand, nine hundred and ninety-nine will be for the Fire, and one for Paradise." This weighed heavily upon the Muslims, so the Prophet, peace and blessings of Allah be upon him, said: "Be upright, draw near [to the truth], and rejoice. For by the One in whose hand is my soul, you are not among the people except like a mole on the side of a camel, or like a mark on the foreleg of a beast. Indeed, there are with you two creations that have never been in anything but they increased it: Gog and Magog, and those who perished from the disbelievers among the jinn and mankind."