Notes mostly from Shaikh Jamal Zarabozo Commentary
- Hadith from Imam Nawawi text
- Why the word Nutfah is not part of the Hadeeth
- How it changes meanings of first part - Breathing of soul after Forty days
- Hadith must always take priority over science
- Meanings of Sadiq and Masdooq
Hadith from Imam Nawawi text
عَنْ أَبِي عَبْدِ الرَّحْمَنِ عَبْدِ اللَّهِ بْنِ مَسْعُودٍ رَضِيَ اللهُ عَنْهُ قَالَ: حَدَّثَنَا رَسُولُ اللَّهِ صلى الله عليه و سلم -وَهُوَ الصَّادِقُ الْمَصْدُوقُ-: "إنَّ أَحَدَكُمْ يُجْمَعُ خَلْقُهُ فِي بَطْنِ أُمِّهِ أَرْبَعِينَ يَوْمًا نُطْفَةً، ثُمَّ يَكُونُ عَلَقَةً مِثْلَ ذَلِكَ، ثُمَّ يَكُونُ مُضْغَةً مِثْلَ ذَلِكَ، ثُمَّ يُرْسَلُ إلَيْهِ الْمَلَكُفَيَنْفُخُ فِيهِ الرُّوحَ، وَيُؤْمَرُ بِأَرْبَعِ كَلِمَاتٍ: بِكَتْبِ رِزْقِهِ، وَأَجَلِهِ، وَعَمَلِهِ، وَشَقِيٍّ أَمْ سَعِيدٍ؛ فَوَاَللَّهِ الَّذِي لَا إلَهَ غَيْرُهُ إنَّ أَحَدَكُمْ لَيَعْمَلُ بِعَمَلِأَهْلِ الْجَنَّةِ حَتَّى مَا يَكُونُ بَيْنَهُ وَبَيْنَهَا إلَّا ذِرَاعٌ فَيَسْبِقُ عَلَيْهِ الْكِتَابُ فَيَعْمَلُ بِعَمَلِ أَهْلِ النَّارِ فَيَدْخُلُهَا. وَإِنَّ أَحَدَكُمْ لَيَعْمَلُ بِعَمَلِ أَهْلِالنَّارِ حَتَّى مَا يَكُونُ بَيْنَهُ وَبَيْنَهَا إلَّا ذِرَاعٌ فَيَسْبِقُ عَلَيْهِ الْكِتَابُ فَيَعْمَلُ بِعَمَلِ أَهْلِ الْجَنَّةِ فَيَدْخُلُهَا".
On the authority of Abdullah ibn Masood (ra), who said:
The Messenger of Allah (ﷺ), and he is the truthful, the believed, narrated to us, “Verily the creation of each one of you is brought together in his mother’s womb for forty days in the form of a nutfah (a drop), then he becomes an alaqah (clot of blood) for a like period, then a mudghah (morsel of flesh) for a like period, then there is sent to him the angel who blows his soul into him and who is commanded with four matters: to write down his rizq (sustenance), his life span, his actions, and whether he will be happy or unhappy (i.e., whether or not he will enter Paradise). By the One, other than Whom there is no deity, verily one of you performs the actions of the people of Paradise until there is but an arms length between him and it, and that which has been written overtakes him, and so he acts with the actions of the people of the Hellfire and thus enters it; and verily one of you performs the actions of the people of the Hellfire, until there is but an arms length between him and it, and that which has been written overtakes him and so he acts with the actions of the people of Paradise and thus he enters it.” [Bukhari & Muslim]
Imam Nawawi has an extra word, نطفة which is not in Hadith. See below from Bukhari:
حَدَّثَنَا الْحَسَنُ بْنُ الرَّبِيعِ، حَدَّثَنَا أَبُو الأَحْوَصِ، عَنِ الأَعْمَشِ، عَنْ زَيْدِ بْنِ وَهْبٍ، قَالَ عَبْدُ اللَّهِ حَدَّثَنَا رَسُولُ اللَّهِ صلى الله عليهوسلم وَهْوَ الصَّادِقُ الْمَصْدُوقُ قَالَ " إِنَّ أَحَدَكُمْ يُجْمَعُ خَلْقُهُ فِي بَطْنِ أُمِّهِ أَرْبَعِينَ يَوْمًا، ثُمَّ يَكُونُ عَلَقَةً مِثْلَ ذَلِكَ، ثُمَّ يَكُونُ مُضْغَةًمِثْلَ ذَلِكَ، ثُمَّ يَبْعَثُ اللَّهُ مَلَكًا، فَيُؤْمَرُ بِأَرْبَعِ كَلِمَاتٍ، وَيُقَالُ لَهُ اكْتُبْ عَمَلَهُ وَرِزْقَهُ وَأَجَلَهُ وَشَقِيٌّ أَوْ سَعِيدٌ. ثُمَّ يُنْفَخُ فِيهِ الرُّوحُ، فَإِنَّالرَّجُلَ مِنْكُمْ لَيَعْمَلُ حَتَّى مَا يَكُونُ بَيْنَهُ وَبَيْنَ الْجَنَّةِ إِلاَّ ذِرَاعٌ، فَيَسْبِقُ عَلَيْهِ كِتَابُهُ، فَيَعْمَلُ بِعَمَلِ أَهْلِ النَّارِ، وَيَعْمَلُ حَتَّى مَا يَكُونُبَيْنَهُ وَبَيْنَ النَّارِ إِلاَّ ذِرَاعٌ، فَيَسْبِقُ عَلَيْهِ الْكِتَابُ، فَيَعْمَلُ بِعَمَلِ أَهْلِ الْجَنَّةِ ".
Narrated `Abdullah bin Mus'ud:
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 during the same period, and then a piece of flesh during the same 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." (Translation from )
الصادق - the one who is truthful in everything he says. 
المصدوق - the one who is to be believed in 
Regarding added word Nutfah
Extra word in Hadith 4 of Forty Hadeeth by Imam An-Nawawi changes meanings in relation to three stages and number of days. The word may have been added for clarity but somehow remained. 
Al Qadhaah wrote,
The word nutfah has been [incorrectly] added to the text. It is not mentioned in any of the existing sources of the sunnah. However, it is found in some of the books of the later writers, such as hadith number 4 of al-Nawawi's 40 Hadith. It seems that it was mentioned to make the sentence clearer and, then, afterwards the people thought it was part of the hadith and included it as such. In reality, the existence of that word in the hadith changes in some way the meaning of the hadith. While the original text of the hadith makes it clear that the fetus goes through all three stages (nutfah, alaqah and mudhghah) in the first forty days. The added word gives a different meaning. According to the wrong narration, the stages take place in the first four months. It is clear from modem day science that such is not correct. This hadith also demonstrates one of the many scientific "miracles" that one finds in the hadith with authentic narrations. 
Science versus Islam 
The Prophet (peace be upon him) received revelation from and was guided by Allah. There is no room to doubt anything that he said, regardless of the topic. Allah would not leave him to make mistakes and misguide people. This is an insult to Allah Himself. Unfortunately, due to modem-day advancements in science, people have a tendency to forget that there is a great difference between scientific theory and established fact. Much of what people believe in and accept today is nothing more than theory and hypothesis that cannot be established with certainty. Indeed, in one hundred years or so, these theories may be discarded in favor of stronger theories. In fact, this process occurs everyday today in the realm of science.
If the Prophet (peace be upon him) has said something or if a verse in the Quran states something, then that must be true. If it does not seem to mix with one's perception of reality and "scientific fact", then either one has misunderstood the hadith or verse or one's perception ofreality is incorrect. In any case, there is no room to doubt the Prophet (peace be upon him) for he is, as ibn Masood stated, the truthful, the one to be believed. Otherwise, there cannot be anything that exists in this world that contradicts what has been revealed from Allah. This is because this creation and the revelation the Prophet (peace be upon him) received both come from the same source: Allah. Allah is All-Knowledgeable and is most Truthful in His Speech. Hence, there will never be any contradiction between something that is a reality in the physical world and what Allah has revealed to any of His prophets.
1. Hadith 4 of أربعين انواوى commentary by Zarabozo pp.323-
Compiled: by Ishaq Zahid
(my notes are limited to the first part on Nutfah as of 5/8/2023)