Musnad Ahmad 937:31

'Affan narrated to us, 'Abd al-Wahid ibn Ziyad narrated to us, al-Harith ibn Hasirah narrated to us, Zayd ibn Wahb narrated to us, he said: Abu Dharr said: "That I should swear ten times that Ibn Sa'id is the Dajjal is more beloved to me than that I should swear once that he is not him." He said: The Messenger of Allah (peace and blessings of Allah be upon him) sent me to his mother and said: "Ask her how long she carried him." He said: So I went to her and asked her, and she said: "I carried him for twelve months." He said: Then he sent me to her and said: "Ask her about his cry when he fell [was born]." He said: So I returned to her and asked her, and she said: "He cried the cry of a month-old infant." Then the Messenger of Allah (peace and blessings of Allah be upon him) said to him: "I have hidden something for you." He said: "You have hidden for me the snout of a dusty-colored sheep and the smoke (al-dukhan)." He said: So he wanted to say "the smoke," but he could not, so he said: "al-dukh, al-dukh." The Messenger of Allah (peace and blessings of Allah be upon him) said: "Be driven away (ikhsa'), for you will never exceed your limit."