Musnad Ahmad 26:384

Husayn ibn Muhammad narrated to us, Fitr narrated to us, from Salamah ibn Kuhayl, from Zayd ibn Wahb al-Juhani, from Abdullah ibn Mas’ud, who said: I heard the Messenger of Allah, peace and blessings of Allah be upon him, saying—and he is the truthful, the believed: "The creation of one of you is gathered in the womb of his mother for forty nights, then he becomes a clinging clot for the like of that, then he becomes a chewed-like lump for the like of that. Then Allah, the Almighty and Majestic, sends an angel to him, and he says: 'Write his deeds, his lifespan, and his provision, and write him as miserable or happy.'" Then he said: "By the One in Whose hand is the soul of Abdullah, indeed a man performs the deeds of the people of Paradise until there is not between him and Paradise but a cubit, then misery overtakes him, so he performs the deeds of the people of the Fire, and he dies, and enters the Fire." Then he said: "By the One in Whose hand is the soul of Abdullah, indeed a man performs the deeds of the people of the Fire until there is not between him and the Fire but a cubit, then happiness overtakes him, so he performs the deeds of the people of Paradise, and he dies, and enters Paradise."