Sahih Muslim 2643 a

Allah's Messenger (ﷺ) , the true and truly inspired said, "(The matter of the Creation of) a human being is put together in the womb of the mother in forty days, and then he becomes a clot of thick blood for a similar period, and then a piece of flesh for a similar period. Then Allah sends an angel who is ordered to write four things. He is ordered to write down his (i.e. the new creature's) deeds, his livelihood, his (date of) death, and whether he will be blessed or wretched (in religion). Then the soul is breathed into him. So, a man amongst you may do (good deeds till there is only a cubit between him and Paradise and then what has been written for him decides his behavior and he starts doing (evil) deeds characteristic of the people of the (Hell) Fire. And similarly a man amongst you may do (evil) deeds till there is only a cubit between him and the (Hell) Fire, and then what has been written for him decides his behavior, and he starts doing deeds characteristic of the people of Paradise."

Allah's Messenger (ﷺ) , the truthful and truly-inspired, said, "Each one of you collected in the womb of his mother for forty days, and then turns into a clot for an equal period (of forty days) and turns into a piece of flesh for a similar period (of forty days) and then Allah sends an angel and orders him to write four things, i.e., his provision, his age, and whether he will be of the wretched or the blessed (in the Hereafter). Then the soul is breathed into him. And by Allah, a person among you (or a man) may do deeds of the people of the Fire till there is only a cubit or an arm-breadth distance between him and the Fire, but then that writing (which Allah has ordered the angel to write) precedes, and he does the deeds of the people of Paradise and enters it; and a man may do the deeds of the people of Paradise till there is only a cubit or two between him and Paradise, and then that writing precedes and he does the deeds of the people of the Fire and enters it."

Allah's Messenger (ﷺ) , the true and truly inspired said, "(as regards your creation), every one of you is collected in the womb of his mother for the first forty days, and then he becomes a clot for another forty days, and then a piece of flesh for another forty days. Then Allah sends an angel to write four items: He writes his deeds, time of his death, means of his livelihood, and whether he will be wretched or blessed (in religion). Then the soul is breathed into his body. So a man may do deeds characteristic of the people of the (Hell) Fire, so much so that there is only the distance of a cubit between him and it, and then what has been written (by the angel) surpasses, and so he starts doing deeds characteristic of the people of Paradise and enters Paradise. Similarly, a person may do deeds characteristic of the people of Paradise, so much so that there is only the distance of a cubit between him and it, and then what has been written (by the angel) surpasses, and he starts doing deeds of the people of the (Hell) Fire and enters the (Hell) Fire."

Allah's Messenger (ﷺ) the true and truly inspired, narrated to us, "The creation of everyone of you starts with the process of collecting the material for his body within forty days and forty nights in the womb of his mother. Then he becomes a clot of thick blood for a similar period (40 days) and then he becomes like a piece of flesh for a similar period. Then an angel is sent to him (by Allah) and the angel is allowed (ordered) to write four things; his livelihood, his (date of) death, his deeds, and whether he will be a wretched one or a blessed one (in the Hereafter) and then the soul is breathed into him. So one of you may do (good) deeds characteristic of the people of Paradise so much that there is nothing except a cubit between him and Paradise but then what has been written for him decides his behavior and he starts doing (evil) deeds characteristic of the people of Hell (Fire) and (ultimately) enters Hell (Fire); and one of you may do (evil) deeds characteristic of the people of Hell (Fire) so much so that there is nothing except a cubit between him and Hell (Fire), then what has been written for him decides his behavior and he starts doing (good) deeds characteristic of the people of Paradise and ultimately) enters Paradise." (See Hadith No. 430, Vol. 4)

The Messenger of Allah (ﷺ) who spoke the truth and whose word was belief told us the following : The constituents of one of you are collected for forty days in his mother’s womb, then they become a piece of congealed blood for a similar period, then they become a lump of flesh for a similar period. Then Allah sends to him an angel with four words who records his provision the period of his life, his deeds, and whether he will be miserable or blessed ; thereafter he breathes the spirit into him. One of you will do the deeds of those who go to Paradise so that there will be only a cubit between him and it or will be within a cubit, then what is decreed will overcome him so that he will do the deeds of those who go to Hell and will enter it; and one of you will do the deeds of those who go to hell, so that there will be only a cubit between him and it or will be within a cubit, then what is decreed will overcome him, so that he will do the deeds of those who go to Paradise and will enter it.

"The Messenger of Allah (ﷺ), the true and truly inspired one, told us that: 'The creation of one of you is put together in his mother's womb for forty days, then it becomes a clot for a similar length of time, then it becomes a chewed lump of flesh for a similar length of time. Then Allah sends the angel to him and commands him to write down four things. He says: "Write down his deeds, his life span, his provision, and whether he is doomed (destined for Hell) or blessed (destined for Paradise)." By the One in Whose Hand is my soul! One of you may do the deeds of the people of Paradise until there is no more than a forearm's length between him and it, then the decree overtakes him and he does the deeds of the people of Hell until there is no more than a forearm's length between him and it, then the decree overtakes him and he does the deeds of the people of Paradise until he enters therein."