"Belief in Al-Qadar" (the divine will and decree) is one of the pillars of faith, Allah has decreed all things from eternity and knows that they will happen at times that are known to Him, and in specific ways, and that He has written that and willed it, and they happen according to what He has decreed.
Al-Qadr is an Arabic word meaning Allah’s predestination of measurements and sustenance of everything and everyone, according to His Knowledge and Wisdom.
It comprises the following four aspects - Knowledge, Pre-recording, Will of Allah, and Creation.
1. Knowledge: The perception that the knowledge of Allah (swt) includes every matter, major or minor, and the time frame of all that exists in this world. Allah’s knowledge can’t be compared to any other knowledge in creation. Our knowledge is preceded by ignorance and we gain knowledge by learning. We also forget. How many times have we studied something only to forget it the next day? Allah’s ‘ilm is neither acquired through learning nor preceded by ignorance; nothing in the heavens or on Earth escapes His notice. Allah (swt) says in the Quran:
۞ وَعِندَهُۥ مَفَاتِحُ ٱلْغَيْبِ لَا يَعْلَمُهَآ إِلَّا هُوَ ۚ وَيَعْلَمُ مَا فِى ٱلْبَرِّ وَٱلْبَحْرِ ۚ وَمَا تَسْقُطُ مِن وَرَقَةٍ إِلَّا يَعْلَمُهَا وَلَا حَبَّةٍۢ فِى ظُلُمَـٰتِ ٱلْأَرْضِ وَلَا رَطْبٍۢ وَلَا يَابِسٍ إِلَّا فِى كِتَـٰبٍۢ مُّبِينٍۢ
With Him are the keys of the unseen—no one knows them except Him. And He knows what is in the land and sea. Not even a leaf falls without His knowledge, nor a grain in the darkness of the earth or anything—green or dry—but is ˹written˺ in a perfect Record. (Surah 6:59)
وَهُوَ ٱلَّذِى يَتَوَفَّىٰكُم بِٱلَّيْلِ وَيَعْلَمُ مَا جَرَحْتُم بِٱلنَّهَارِ ثُمَّ يَبْعَثُكُمْ فِيهِ لِيُقْضَىٰٓ أَجَلٌۭ مُّسَمًّۭى ۖ ثُمَّ إِلَيْهِ مَرْجِعُكُمْ ثُمَّ يُنَبِّئُكُم بِمَا كُنتُمْ تَعْمَلُونَ
He is the One Who calls back your souls by night and knows what you do by day, then revives you daily to complete your appointed term. To Him is your ˹ultimate˺ return, then He will inform you of what you used to do. (Surah 6:60)
Allah (swt) is so perfect in all His attributes that no created being can be equal to Him in any of the attributes. Out of these attributes two are most distinct; `Ilm [knowledge] and Qudrah [power]. His (swt) knowledge encompasses and embraces all. His Power surrounds and controls everything fully and conclusively. The above ayahs describe these two attributes. If one believed in these two attributes strongly and completely he just cannot ever even think of committing a crime or sin. A person remains conscious and knows that there is someone All-Knowing, All-Aware, All-Powerful watching over him all the time, and Who knows him outside in and inside out and Who is aware of even the intention of the heart and the passing thought of the mind, then, how would he ever be able to take even a tiny step towards any disobedience to his All-Powerful Master? The keys to the Unseen are with Allah subhanahu wa ta`ala alone. They are in His possession and ownership. Bukhari recorded that Salim ibn `Abdullah said that his father said that the Messenger of Allah (pbuh) said,
مَفَاتِيحُ الْغَيْبِ خَمْسٌ لَا يَعْلَمُهُنَّ إِلَّا الله
“The keys of the Unseen are five and none except Allah knows them.”
Allah (swt) describes these five Unseen matters in Surah Luqman Ayah 34 -
إِنَّ ٱللَّهَ عِندَهُۥ عِلْمُ ٱلسَّاعَةِ وَيُنَزِّلُ ٱلْغَيْثَ وَيَعْلَمُ مَا فِى ٱلْأَرْحَامِ ۖ وَمَا تَدْرِى نَفْسٌۭ مَّاذَا تَكْسِبُ غَدًۭا ۖ وَمَا تَدْرِى نَفْسٌۢ بِأَىِّ أَرْضٍۢ تَمُوتُ ۚ إِنَّ ٱللَّهَ عَلِيمٌ خَبِيرٌۢ
Indeed, Allah ˹alone˺ has the knowledge of the Hour. He sends down the rain, and knows what is in the wombs. No soul knows what it will earn for tomorrow, and no soul knows in what land it will die. Surely Allah is All-Knowing, All-Aware.
Allah (swt) further states that He knows whatever there is on the land and in the sea. His knowledge encompasses everything, including the creatures living in the sea and on land, and none of it, not even the weight of an atom on earth or in heaven, ever escapes His knowledge. He knows the movements of everything including inanimate things. Therefore, what can be said about His knowledge of the living creatures, especially, those whom the Divine laws have been imposed upon such as mankind and the Jinns.
2. Pre-recording: The belief that Allah recorded everything in a Tablet that He kept with Himself, called 'Al-Lawh Al-Mahfooth' (The Preserved Tablet). Allah (swt) says in the Quran, Surah Al-Hajj, 22:70 -
اَلَمۡ تَعۡلَمۡ اَنَّ اللّٰهَ يَعۡلَمُ مَا فِى السَّمَآءِ وَالۡاَرۡضِؕ اِنَّ ذٰ لِكَ فِىۡ كِتٰبٍ ؕ اِنَّ ذٰ لِكَ عَلَى اللّٰهِ يَسِيۡرٌ
Are you not aware that Allah knows all that is in the heaven and the earth? Surely it is all preserved in a Book. Indeed that is easy with Allah. Ibn Kathir (may Allah have mercy on him) said: “In ‘al-Lawh al-Mahfuz (the Preserved Tablet)’ means, it is among the higher group (i.e., angels), preserved and protected from anything being added or taken away, or any alteration or changes.” (Tafsir Ibn Kathir, 4/497, 498). Ibn al-Qayyim (may Allah have mercy on him) said: “Preserved: most readers recite this with a kasrah, i.e., it is a description of the Lawh. This indicates that the shayatin are not able to bring it down, because its location is protected and they cannot reach it. And it is itself protected, so the Shaytan cannot add anything to it or take anything away from it. Allah (swt), has described it as protected or guarded in the ayah:
إِنَّا نَحْنُ نَزَّلْنَا ٱلذِّكْرَ وَإِنَّا لَهُۥ لَحَـٰفِظُونَ
Verily, We, it is We Who have sent down the Dhikr (i.e. the Quran) and surely, We will guard it (from corruption). (Surah Al-Hijr 15:9). And its location is also described as being guarded in this surah. Allah (swt), is protecting its location, and protecting it from having anything added or taken away, or being distorted. He is protecting its meanings from being twisted, just as He is protecting its words from being changed, and He is protecting its letters so that nothing is added or taken away.” (al-Tabyan fi Aqsam al-Quran, p. 62).
3. Will: The belief that nothing, whether related to Allah’s actions or actions taken by His slaves, can occur without His permission. Allah (swt) Says in the Quran:
وَرَبُّكَ يَخْلُقُ مَا يَشَآءُ وَيَخْتَارُ ۗ مَا كَانَ لَهُمُ ٱلْخِيَرَةُ ۚ سُبْحَـٰنَ ٱللَّهِ وَتَعَـٰلَىٰ عَمَّا يُشْرِكُونَ
Your Lord creates and chooses whatever He wills—the choice is not theirs. Glorified and Exalted is Allah above what they associate ˹with Him˺! (Surah 28:68)
وَيَفْعَلُ ٱللَّهُ مَا يَشَآءُ - هُوَ ٱلَّذِى يُصَوِّرُكُمْ فِى ٱلْأَرْحَامِ كَيْفَ يَشَآءُ ۚ
لَآ إِلَـٰهَ إِلَّا هُوَ ٱلْعَزِيزُ ٱلْحَكِيمُ
For Allah does what He wills. (Surah,14:27) And He is the One Who shapes you in the wombs of your mothers as He wills. There is no god ˹worthy of worship˺ except Him—the Almighty, All-Wise. (Surah, 3:6)
وَلَوْ شَآءَ ٱللَّهُ لَسَلَّطَهُمْ عَلَيْكُمْ فَلَقَـٰتَلُوكُمْ ۚ
وَلَوْ شَآءَ ٱللَّهُ مَا فَعَلُوهُ ۖ فَذَرْهُمْ وَمَا يَفْتَرُونَ
As for actions taken by His (swt) creation, Allah (swt) Says “…And if Allah had willed, He could have given them power over you, and they would have fought you.” (Surah, 4:90) And “…And if Allah had willed, they would not have done so. So leave them and that which they invent.” (Surah 6:137)
4. Creation: The belief that Allah (swt) created all creation, all what they possess of attributes, and all their actions. Allah (Swt) Says in the Quran -
ٱللَّهُ خَـٰلِقُ كُلِّ شَىْءٍۢ ۖ وَهُوَ عَلَىٰ كُلِّ شَىْءٍۢ وَكِيلٌۭ
وَخَلَقَ كُلَّ شَىْءٍۢ فَقَدَّرَهُۥ تَقْدِيرًۭا
وَٱللَّهُ خَلَقَكُمْ وَمَا تَعْمَلُونَ
“Allah is the Creator of all things, and He is, over all things, Disposer of affairs.” (Surah 39:62) And: “…He has created each thing and determined it with [precise] determination.” (Surah 25:2) Also, Ibraheem (as) said to his people: “While Allah created you and that which you do?” (Surah 37:96)
Belief in Al-Qadr, as explained above, does not provide an excuse for mankind to sin or abandon what they are obligated to do.
Allah (swt) says in the Quran -
1. “Those who associated with Allah will say: 'If Allah had willed, we would not have associated [anything] and neither would our fathers, nor would we have prohibited anything.' Likewise did those before deny until they tasted Our punishment. Say: 'Do you have any knowledge that you can produce for us?' You follow not except assumption, and you are not but falsifying.” (Surah 6:148)
2. “[We sent] messengers as bringers of good tidings and warners so that mankind will have no argument against Allah after the messengers. And ever is Allah Exalted in Might and Wise.” (Surah 4:165)
3. “So fear Allah as much as you are able…” (Surah 64:16) And: “Allah does not charge a soul except [with that within] its capacity…” (Surah 2:286)
This is mankind cannot use Al-Qadr as an excuse for not believing, because Al-Qadr provided them with the means to escape Allah’s punishment by following His Messengers. Allah (swt) conveyed His commandments to His slaves and did not require them to do what is beyond their capacity; If the slave is forced to do whatever deeds he performs, then Allah would have required from him what is beyond his capacity, and this is a false belief. For this reason, Allah forgives sins that take place because of ignorance or forgetfulness.
Al-Qadr is a matter of Allah’s Knowledge. No one can uncover his own Qadr except after it occurs. One’s intention to perform a deed precedes the action itself. He does not know what Al-Qadr holds for him. Therefore, Al-Qadr is not a valid excuse for sinning and abandoning the commandments of Allah.
Rest Allah (swt) knows best.
Source: Quran, Tafsir Ibn kathir, In the shade of the Quran, Hadith, Sunnah.com, Islam QA