We all experience doubt.
Am I on the 2nd or 3rd rakat?
Do I still have wudhu?
How many days of fasting was I supposed to make up from last Ramadan?
And the list goes on and on.
Thankfully, Islam has simple principles regarding doubt and ways to address and remedy it. I've rounded up a collection of helpful resources regarding doubt whether you are having issues of doubt in your faith or certain acts of worship such as prayer and fasting.
A Tremendous Principle which brings Ease to the Muslims – Shaykh Al-Uthaymīn
"Every Muslim who has ever had doubt regarding their prayer or other act of worship, or knows someone who is or has been afflicted with whispers from the Shaytān which affect their worship and make them believe it wasn’t completed, wasn’t performed properly, they were not in purification (if it is required) then you will find in the explanation of Shaykh Al-Uthaymīn much enlightenment...."
Goes over several cases where doubt may creep in and what to do (e.g. doubt in number of completed rakaat, doubt in the number of missed prayers and fasts)
I Have Constant Doubts About My Faith. Does This Make Me A Hypocrite? – Shaykh Muhammad Bazmool
Readings in Kashf ush-Shubuhaat (Removal of the Doubts) - 11 lessons (PDF)
Advice for a Person who is Immersed in Desires and Doubts – Shaykh Rabee
Shaykh Rabee ibn Haadi Al-Madkhalee (hafidahullah) was asked:
What is your advice – Allah preserve you – to the one who has fell [sic] into the sea of desires and doubts?
My advice to him is that he repents to Allah and that he brings to mind the statement of Allah:
قُلْ يَا عِبَادِيَ الَّذِينَ أَسْرَفُوا عَلَىٰ أَنفُسِهِمْ لَا تَقْنَطُوا مِن رَّحْمَةِ اللَّهِ إِنَّ اللَّهَ يَغْفِرُ الذُّنُوبَ جَمِيعًا إِنَّهُ هُوَ الْغَفُورُ الرَّحِيمُ
Say: “O ‘Ibadi (My slaves) who have transgressed against themselves (by committing evil deeds and sins)! Despair not of the Mercy of Allah, verily Allah forgives all sins. Truly, He is Oft-Forgiving, Most Merciful. [Az-Zumar: 53]
So if you swam in the sea of disbelief for you is to exit with repentance to Allah (tabaaraka wa ta’aala), therefore upon him is to repent to Allah and return to Allah, the door of repentance is open for all of the servants (of Allah).
Explanation of The Book, "Doubts Surrounding Islām and How To Respond To Them" -
Set of 24 audio lessons from 2020-2021 on a range of topics that includes: slavery in Islam, Islamic punishments, the idea that Islam was spread by the sword, the idea that Islam is oppressive to women, polygyny, and the marriages of the Prophet (sallAllahu alayhi wa sallam)
Written and Taught by Shaykh Abū ‘Ammār Alī al-Ḥudhayfī of Yemen