I heard the Messenger of Allah (ﷺ), who is the most truthful one, (say):

"The creation of any one of you is put together in his mother's womb for forty days, then he becomes a 'alaqah (a piece of thick coagulated blood) for a similar period, then he becomes like a chewed piece of flesh (mudghah) for a similar period, then Allah sends to him one of the angels and says: ‘Write down his deeds, his lifespan, his provision, and write down whether he is doomed (to Hell) or blessed (destined for Paradise).’" Then he said: By the One in whose hand is the soul of `Abdullah, a man may do the deeds of the people of Paradise until there is nothing between him and Paradise but a cubit, then the misfortune overtakes him and he does the deeds of the people of Hell, then he dies and enters Hell. Then he said: By the One in Whose hand is the soul of ‘Abdullah, a man may do the deeds of the people of Hell until there is nothing between him and Hell but a cubit, then the good fortune overtakes him and he does the deeds of the people of Paradise, then he dies and enters Paradise.